hello and welcome to inside of thermology this is Dr Amrit welcoming you to another video on lens in our previous video we studied about the anatomy of lens and in this video we shall be studying about the classification of the Cataract in particular our Focus will be on the age-related Cataract or the senile cataracts and its stages so what is meant by cataract basically we know that the lens is a transparent structure which is present inside the eye which has an important refractive value it basically allows the light to pass through the through it and then focus on the retina now the lens is quite clear and transparent and that happens because of the regular arrangement of the fibers what I explained to you in the anatomy of the lens apart from that the lens fibers do not have any organelles if a structure or if a cell has organelles in it what happens is that the light will get scattered okay and therefore to avoid scattering of the light God has made our lens in such a way that it does not have any kind of organelles right so whenever this transparency of the lens is lost they will be opacification or cloudiness of the lens and that is called catch track now did you know that the term cataract is actually derived from the Greek word for waterfalls okay so this waterfall if you see actually has this rapidly flowing water it actually because of the rapid flow uh the rapidness of the flow of water the waterfall looks cloudy okay and therefore the senile cataract appearance is also like into a rapidly flowing white water and therefore this term cataract was derived now coming to the classification of the Cataract so basically there are two classifications in which we can divide cataracts into one is based on uh how does the Cataract develop so that is called an etiological classification and then we have a classification based on how the Cataract looks like okay so that is called a morphological classification first of all let us talk about the etiological classification okay in etiological classification we basically have two types number one is the congenital cataract or the developmental Catra now as the name suggests they will develop at Birth or during the uh during the time period when the lens is actually developing okay and this happens because of some disturbance in the normal lens development or the formation of lens fibers okay now we already have a video on the embryology of the lens and the video is titled as the development of the lens so in which I have explained to you in detail regarding the formation of the lens fibers so whenever there is some disturbance in the formation of the lens fibers during the developmental period it leads to the developmental cataract right now after the lens fibers have been formed and if there is some trigger triggering Factor okay which causes degeneration of those already formed lens fibers then the Cataract which we get is called an acquired cataract now there are about more than 10 types of acquired cataracts so we will make a separate video on developmental Cataract and a separate video on various types of acquired cataracts however in this video we shall be focusing on the senile cataract or the age-related Cataract which is also a most which is actually the most common type of the acquired Catra now based on the morphology based on how the Cataract looks like we have different types of cataracts so the Cataract or the opacification of the lens which occurs just at the capsular level of the lens is called a capsular cataract now if the opacification occurs just beneath the capsule so that is called a sub capsular cataract now if this opacification is occurring along the anterior surface it is called an anterior sub capsular Cataract and if the opacification is occurring along the posterior surface that is called a posterior subcapsular cataract okay so sub capsular cataract mean the cortex which is present just beneath the capsule will get opacified okay now the next type of cataract is the cortical cataract so in the cortical cataract your cortex is going to get affected right so that is called a cortical cataract if the nucleus gets obesified or sclerosis so that's called a nuclear cataract if the poles of the lens is going to get affected that means part of your capsule at the pole part of your sub capsular area or the cortex at the pole then that is called a polar cataract right now this polar cataract again can be an anterior polar cataract or it can be a posterior polar cataract based on where the opacification is taking place now this is a very important clinical difference between the Developmental and the acquired cataract that you must remember so the developmental cataract or the developmental opacities as I told you they developed during the developmental period of the lens fibers right now these opacities are actually partial opacities that means they're not very dense and they're also stationary that means if there's an opacity that you see of a developmental cataract it'll it is likely to stay like this for quite a long period of time even in the adulthood okay of course there are exceptions but the rule of thumb is that the developmental opacities or developmental cataract usually do not progress if you talk about the acquired opacity or an acquired cat rat that actually happens after the lens fibers have developed okay these opacities will actually progress and they progress in such a way that almost they involve the entire lens itself okay of course there there are exceptions to the uh both these rules now let us discuss a main type of a quiet cataract that is the senile cataract also called as the age-related Cataract so in this section we shall be discussing about the various stages of the senile caterer so briefly what is an age-related or a senile cataract as the name suggests it occurs basically as you age and mainly duckers because of lifelong exposure to sunlight or the UV radiation now this the age at which it affects is usually more than 50 years of age okay it's very rare in people who are younger than 50 years of age and that can occur if they have any Associated metabolic disturbances like the diabetes mellitus almost Universal that means above the age of 70 about 90 percent of the people will have this age-related cataract or these senile cataract now the question is what are the risk factors for developing senile cataracts so definitely Asia's age is a risk factor everyone above 50 years uh are at a risk factor to develop senile cataracts and however it has been seen that's Nile cataract can also develop before 45 years of age and if it develops before 45 years of age and if it is not a developmental cataract what you are actually dealing with is a personal cataract okay so a senile cataract that occurs before the age of 45 and some say before the age of 50 is called a pre-senal cataract what about the sex predisposition no males and females are equally affected by the senile cataract so it is basically the ultraviolet radiation exposure it has been seen that if you uh if your eyes are exposed to a lot of UV radiation it causes an early onset and faster maturation of the Cataract now this can be seen by the fact that the average age of onset of cataract is approximately 10 years earlier in tropical countries compared to that in the temperate countries because uh the tropical countries have more sunlight they have more UV radiation so definitely people residing in tropical countries they develop cataract much more earlier right and the reason for this is the changes in the protein structure of the lens that occurs because of exposure to the UV radiation now diet definitely plays a very important role so if you have a diet which is deficient in proteins amino acid vitamins uh like riboflavin vitamin E vitamin C which are the antioxidants definitely the damage which is occurring by the UV radiation you cannot uh your body or your eyes cannot deal with it because of the lack of antioxidant Rich diet similarly it has been seen that if the patient has had any dehydration crisis uh during his lifetime so that could be you know severe episodes of dehydration because of some diarrhea because of severe vomiting episodes so that can also affect uh the metabolism of the lens and that can also lead to cataract formation smoking is definitely a risk factor which actually uh can you know put you at a risk of developing cataract much more earlier it happens because of the accumulation of this pigmented molecules which are associated with smoking okay like the three hydroxychi neuronin and chromophores which will lead to yellowing of the lens apart from that you have these cyanates which will cause the carbonylization of the proteins of the lens and also cause protein denaturation which finally causes the opacification and the cataract so let us briefly understand what exactly happens at the molecular level now as I told you in the video on anatomy of lens the lens fibers are very regularly arranged okay and they have this crystalline protein which is nicely arranged like this and these lens molecules or these fibers if you see they actually do not have any sort of organelles in them now whenever there's a damage to the lens either because of UV radiation or it is because of the smoking molecule so what is happening there is some biochemical changes which are occurring in this crystalline molecule right so crystalline molecules which are orderly present in the lens will now get disordered okay and moreover you don't have a diet which is antioxidant Rich so that leads to unfolding of the crystalline and leads to clouding of the lens and that is what is called as the Cataract okay so I hope that is clear now the question is why do some people develop cataract before the age of 50 right so that is called a personal cataract so their uh the role of hereditary is definitely known it is said that the onset of the Cataract is much more earlier with every successive generation okay so if someone in your family developed cataracts say at the age of 50 there are more chances that you will also develop cataract at the age of 50 or even earlier okay then diabetes is definitely a risk factor which leads to cataract formation much more earlier and it has been seen that diabetes usually causes the nuclear cataract formation ectopic dermatitis and myodel dystrophy are also two disorders which lead to earlier cataract formation and usually they lead to formation of a sub capsular Catra now coming to the types of senile cataract or age-related cataract the senile cataract can basically be divided into two types based on your the area which is getting opacified so if the cortex is getting affected or opacified it is called a cortical Cataract and if the nucleus is getting opacified it is called the nuclear cataract or a nucleus clerotic cataract right now normally it is it has been seen that a cortical cat wrap is usually a soft Cataract and a nuclear cataract is usually a hard cataract to deal with now let us move on to the stages of maturation of a senile cataract so a senile cataract as I told you is a type of acquired Cataract and a quiet cataracts they usually progress compared to the developmental cataract So based on the progression of the Cataract this is what is called the maturation of the Cataract okay there are different stages of these cataract so obviously the stages of maturation are different in a cortical Cataract and stages of maturation are difficult uh are different in case of a nuclear cataract so first let us talk about the stages of maturation in a cortical cataract so to enumerate we have the stage of lamular Separation a stage of incipient cataract formation in which we have two types cuneiform versus cupuliform then we have an immature senile cataract then we have mature senile cataracts and finally the mature becomes hyper mature senile cataract in that we have again two types more gagne and sclerotic Hyper mature senile cataract now let us talk about the first stage of maturity of a senile cataract that is the stage of lamellar Separation now as the name suggests we have the lens fibers which can also be called as the lens lamella so these lens fibers initially will start getting separated from each other and why are they getting separated from each other because of the collection of fluid in between them okay so that is called the stage of lamellar Separation in which there will be demarcation of this cortical fibers because of their separation by the fluid so basically what is happening is that inside the lens there is this changes in the crystalline structure of the lens there are changes in the protein because of the changes in the protein what is happening is your osmotic pressure inside the lens is actually Rising now as the osmotic pressure inside the lens is rising the lens is going to now take in water hello from your aqueous humor right so this water is going to go inside the lens and cause the separation of the lens fibers so this is called stage of lamular Separation okay now it is believed that this stage is actually reversible so what happens is that normally if you see a young patient or a young person the pupil the emptiness that you see inside the pupil okay so I hope that you know that this is an iris and then you have lens the space between the iris is called a pupil right so if you straight away look at the eye you will see this pupil and behind the pupil what is situated is your lens so a clear lens will give a Blackness or a black appearance to your pupil however in the stage of lamular Separation because some of the fluid has come in and there is separation of the lens fibers the pupil color will now change from black to grayish appearance okay apart from that what happens at this stage is that the refractive index of the cortex will also increase okay and because of this fluid Pockets which have formed between the lens now there will be more refractive index there will be increase in reflection and there will be scattering of light and definitely the visual Equity will also get affected now now let's just talk about the second stage of the development uh sorry the second stage of maturation of the senile cataract so this is called stage of incipient cataract the term incipient means early okay so in the stage of lamellar Separation you just had some fluid Pockets that had developed between the lens fibers separating them but now here you will actually see opacities so in the state of incipient cat rep you are actually going to see opacities and these opacities are going to develop with some clear spaces in between them right so there will be some clear spaces and then you're going to have these opacities okay in millions they can appear in the paraphrase they can appear in the center we don't know but these are sectoral alteration right why it is called sectoral because you have these opacities at certain sectors of the lens right so as the sectors are involved these sectors with opacities will have different refractive indices so you have a clear zone of lens which has different refractive index you have an opacity zone of lens which has a different refractive index because of this different refractive index there will be irregularity in the refraction and the patient can actually complain to you about polyopia okay now here's a question for you what sort of polyopia are you going to see in case of a cataract are you going to see uniocular polyopia or do you see a binocular poly Opus so you can tell that answer in the comment section now in this stage of incipient cataract there are two types okay based on the shape of the opacities that you are going to see it is cuneiform senile cataract or it is a cupuliform Sinai Catra first let us talk about the cuneiform variety so in the cuneiform variety you're going to see these wedge shape or triangular shape opacities with clear zones in between them as you can see they are starting at the Equator so they're starting at the periphery of the lens and then they're going to gradually move towards the center now since they are present in the periphery of the lens sometimes you might actually miss them if you examine the patient in a non-diluted pupil so you might need to dilate the pupil and after you dilate the pupil you will see this red shape opacities at the periphery progressing towards the center now the zone or the quadrant where the first appear is the lower nasal quadrant okay so this is your nose this in this quadrant the lower nasal quadrant is where you're going to develop this cuneiform opacities first so in your diffuse elimination or oblique illumination they will look like these grayish opacities I hope they are clear here and they will become more clear in your retro illumination right so in retro elimination you will see this nice red background of the fundus and against that you will see these black color opacity so you can see nicely this wet shape appearance and this is called a cuneiform cataract in the incipient stage of cataract maturation cataract as the name suggests you can remember this cup okay so you have a saucer shape opacity developing and it develops in the posterior aspect of the lens just below the capsule in the central posterior cortex okay so you are going to see it like this so because it is developing just below the capsule it is also called a posterior sub capsular cataract now in contrast to the cuneiform cataract which was developing at the equator or in the Pelfrey your cupidiform cataract is developed in the center and then it's going to extend towards the periphery right now since it's going to be present right at the pupillary axis the vision is going to get affected earlier in case of cubely form Cataract and more so the Neo vision is going to get affected much more compared to distant vision and the reason is that when you look at a near object there will be accommodation and along with accommodation you will have constriction of the pupil which is called meiosis now if the pupil constricts the patient has to look through that part of the lens the light is passing through that part of the lens which is opacified right at the center whereas in case of a cuneiform cataract the opacities are present in the periphery so therefore the vision is not going to get affected since light is not passing through that peripheral area of the leads right so therefore in cupuliform Cataract because it is a central opacity you are going to get new vision affected much more earlier now let us talk about the third stage of the Cataract maturation and that is a stage of immature cataract okay so here the same cubely form or cuneiform cataracts they are going to now start progressing one is going to progress from periphery to center that is a cuneiform the tubular form is going to start progressing or specification from the center to the periphery and it's going to start involving most of your lens fibers so most of your lens fibers with continuous hydration is going to get opacified however not all the lens fibers are getting or specified at this stage and therefore it is called immature cataract so specifications continues but it is not complete you still have some lens fibers which are clear okay so in this stage the lens will have different colors based on actually the amount of opacification but usually if it's just a cortical cataract then you will have a grayish appearance right so the color is difficult to comment on because you often have a nuclear component also and the color varies based upon nuclear component right so I hope that is clear this is called stage of immature senile cataract in which not all your fibers are opacified but most of them are opacifi right so here you as you can see in this picture a crescentic Shadow okay and inside the pupil inside the edge of the pupil okay and that crescentic shadow is called the iris Shadow so I think this will be the correct time to explain to you about the concept of one confusing topic and that is the iris Shadow so to understand that you should know how a shadow is formed so for a shadow you need a light source then you need an object so the object over here will actually be a Iris okay then you need a screen onto which the shadow is going to form or a wall onto which a shadow is going to perform so in this case the shadow of the iris is going to form on the screen and the screen here is your lens okay so as you can see in this diagram in this picture the shadow of the hand is actually formed on the wall but as you can see there is some amount of distance between the object and between the screen on which the shadow is going to be for so as long as this space is present between the object and between the screen is between the screen you are going to see the shadow okay so there is a definite need for space between the object and the screen in order to form a shadow what does that mean it means that if you want to form a shadow of the iris onto the lens there should be some clear space between the iris and between the lens and the clear space in this case means basically some amount of clear lens fiber us okay which is basically seen in case of immature cataract now what if there is no space there is no space means there will be no Shadow so if you're going to place your hand exactly onto the wall you're not going to see The Shadow of Your Hand onto the wall because there's no space present between your hand and the wall similar thing happens in case of your mature cataract so here in the first picture you can see there is space between the object and screen and therefore you see a shadow but in the second stage in the second picture you don't see a shadow because there is no space so what about the iris Shadow now when you take a tall slide and you shine it say from the temporal aspect of the patient eye you are going to see a shadow like this inside the pupil and the shadow is crescentic shaped and which is seen on the temporal aspect of the pupil and this is called an Irish Shadow now in case of an immature cataract what happens is some part of the lens is obesified but there is a part of the lens which is labeled here in blue which is clear and therefore there is a space between the object the object here is the iris and the screen which is the opacified part of the lens okay and this clear space is going to allow you to get a shadow which is called an Irish Shadow right however if you see a mature cat Rack in mature cataract what happens is the process of a specification is complete you do not have any clear lens fibers and therefore in case of a mature cataract there it is literally like putting a hand straight onto the wall so the object that is the iris is straight almost in very close proximity to the lens and therefore you don't have any clear Zone any clear fibers and therefore you do not see any sort of Iris Shadow so this is a very important differentiating point in case of immature cataract on clinically exam on clinical examination you are going to see in Iris Shadow and in case of a mature cataract you do not see an iris Shadow so I hope that is clear so here you can see that the first picture is actually that of an immature cataract and you can actually see in the insert this small Iris Shadow the second picture is that of a nice Pearl like white cataract that is a mature snail Cataract and here you don't see any sort of Shadow so that is the concept of Irish shadow in immature cataract because you have those clear lens fibers between the lens opacity and the iris the iris is going to cast its shadow upon that gray opacity or upon that lens which is going to act as a screen and therefore you get an Irish Shadow but in case of mature cataract the cortex is completely opaque the pupillary margin is lying almost in close proximation with the lens or with the opacities separated just by a thin capsule and therefore you do not see any Shadow so if there's a shadow it's an immature cataract if there's no Shadow it's a mature so till now what did we discuss we discussed about the stage of lamellar Separation the stage of insip in Cataract and the stage of immature cataract now in that stage of immature cataract you should also understand one cataract which is also just a stage in the progression of maturity it is an intimacy and gadra so what is meant by intimation cataract now basically what is happening in Cataract maturation the lens has this osmotic pressure and it is actually absorbing all the fluid from the aqueous humor now in some patient what happens at the stage of immaturity is that the osmotic pressure might increase so much that a lot of fluid is going to start getting absorbed into the lens so much that a lot of pressure is going to build inside that lens fibers okay or inside the lens the lens is now going to get swollen a swollen lens is called an intumescent lens and therefore such a cataract is called a intumescent cataract okay so in this intuition cataract you can see because of that increase osmotic pressure inside the lens the lens is continuously absorbing increased amount of aqueous is getting swollen and you can see this shiny reflexes okay that is nothing but your stretched glistening capsule and such a lens is called a intimacy cataractus lens now as the lens gets swollen it is good now as the lens gets swollen in case of an intimacy and cataract you can see the a position between the iris and lens occurs this is called an irado lenticular contact now because of that opposition you can see that the aqueous flow from the post seated chamber to the anterior chamber is actually limited and more amount of aqueous is going to get trapped in the posterior chamber further pushing the iris forward and ultimately the block there would also be a blockage or there'll also be a disruption on the flow of aqueous into the angle of the eye right so what is happening the cause of the intuition cataract is that you are developing a pupillary block and ultimately you are developing glaucoma and since this glaucoma is occurring because of the morphological changes in the lens of an intimacy cataract this type of glaucoma is called a fakeomorphic glaucoma so what is the type of cataract that causes phicomorphic glaucoma the answer is you're intimacent cataract so in this picture you can see that if you do a slit lamp examination putting a slit across the eye you can see the space between the iris and the cornea is almost obliterated apart from that you can see this microcystic corneal edema okay which tells you that the intraocular pressure is actually raised and what you are dealing with is a case of a fakeomorphic glaucoma the pupil itself you can see it's it's actually mid dilated pupil and in the second picture you can see that there is this intuition cataract so definitely an intermission cataract the slide actually uh tells you that random Mission cataract can lead to development of a fakeomorphic glaucoma coming to the fourth stage of the maturity of the senile cataract is the stage of mature snail cataract when the all when all the lens fibers will become opacified and therefore the entire cataract is now completely developed and therefore it is called a mature senile catry the whole cortex is involved the no there will not be any Irish Shadow seen because none of the cortex cortical fibers are clear and however if there was intuition intuition changes in the immature stage definitely they will be into Mission which will continue in the mature stage as well the color of the senile cataract is important it is often described as pearly white color and many people call this mature senile cat wrapped also a ripe cataract okay so second picture here demonstrates to you a mature senile cataract Now by this time most of the patients get operated however if a patient neglects a cataract with a mature cataract is left Institute there will be hyper maturity that sets in now what is this hyper maturity basically there are two types of hyper mature syniled caterer one is your more gaglion hyper mature phenylketra and the other one is the sclerotic type of hyper mature senile cataract let us first talk about the morganian hyper mature cataract so what happens in the morganian hyper mature cataract is that now we know that in the process of maturity the lens was continuously absorbing fluid and lens was continuously undergoing hydration right now here in the stage of hyper maturity the pacified lens will now undergo liquefaction the whole cortex will get liquefied so what is left is now a nucleus and the brown color nucleus is going to be sinking down at the bottom of that liquefied bag of Milky fluid okay so the entire cortex is liquefied so you the cortex is actually represented by a back which is filled up with that milky fluid and the lens or the nucleus is sitting right at the bottom okay so there's a demarcation semicircular line you can see this is a demarcation between the cortex and between the nucleus this nucleus is actually quite mobile inside this Milky bag so if you alter the position of the head of the patient the nucleus is actually going to move side to side okay sometimes in this more gagne hyper mature cataract you will see certain calcific deposits okay on the anterior capsule so that is also one thing that you should remember so such a type of hyper mature cataract is called a more gagne and Hyper mature cataract coming to this clerotic variety of hyper mature cataracts now in the Morgan the entire cortex got liquefied and converted into a Milky bag but here the cortex is going to get disintegrated and will get actually organized into a paltaceous mass okay so here the cortex is actually shrinking and it is becoming inspicated right so as the volume of the cortex or the lens is actually decreasing the the capsule what is going to happen to the capsule which was covering the lens the capsule is now going to get wrinkled because the inner Mass has decreased the capsule will develop this wrinkling that you can see in the picture right apart from that there will be thickening of the capsule surface also because whatever cuboidal cells are present in the anterior capsule that will also start proliferating and there will be development of this capsular cataract also at the pole of the lens apart from that one more thing we should remember is that since the lens has shrunken the lens has become smaller okay it is actually occupying now lesser space compared to what it was occupying before right so the tautness of the iris also goes away and the ice will now become tremulous Tyrus will be shaking if you ask the patient to move his eyes from left to right you can see the movement or trembleness of the iris and that is called iridodonisis sometimes because of the weakness of the zonules you can also see the lens trembling and that is called fake codonuses okay so if you see movement of the lens that is called fetco donuses because the term fake applies to lens and iridocious means tremulousness of the iris now what will happen to the lens uh what will happen to the anterior chamber in case of intimacy and cataract the lens was swollen and therefore the anterior chamber was shallow but here since the lens is actually shrunken the lens mass is decrease in case of sclerotic hyper mature cataract the anterior chamber will be deeper okay and ultimately the zonules can also become weaker and this lens can actually also undergo some sort of subluxation so here you can see the first picture is that of a mature cat drag second or first clerotic hyper mature cataract third is a more Gagnon type and the fourth one is actually a morganian in which this Milky fluid can actually get reabsorbed on its own and what you're left with is a nucleus okay and the upper part you can see is actually the opposed anterior posterior capsule so basically you have the lens like this okay in the more gagging if you do a slit this is how it look like so this is your anterior capsule this is your posterior capsule and this is your nucleus right now as this Milky fluid is going to disappear on its own what will happen is that they are going to get opposed to each other the anterior and posty are going to get opposed to each other and the nucleus will be sinking at the bottom right so this is how we are going to see it on the slit section okay apart from that what you're going to see this white structures are nothing but they are the anterior capsular opacifications which you see in case of a Morgan cataract right so the fourth picture actually is that of a total equifaxion and absorption of the cortex with inferior sinking of the lens which can be seen in case of a morganian Catra are you still with me so if you are and if you are liking the video give this video a thumbs up and subscribe to the channel now let us go ahead with the maturation of the nuclear senile cataract okay so whatever we were studying till now was about the maturation of a corticals in alcat rack now we are going ahead with the nuclear senile cataract so nuclear senile cataract begins in the nucleus as the name suggests okay the hardening of pacification is going to start in the nucleus and then it's going to spread to the paraphrase it spreads very slowly compared to your cortical cataract the age of development can be earlier compared to that of the cortical cataract okay so that is important thing now this nuclear cataracts can actually have different sort of colors it can look cloudy in the beginning but then because of the changes which occur in the amino acid tryptophan okay which is altered by the sunlight you will have different tints to a nuclear cataract so if you see a brown color tint as I showed you here okay it is called a cataracta Bruno sense which is called a brown cataract if it gives a black color appearance it's called cataracter and if it gives a red color appearance it's called a red cataract or cataracter rubra now let me tell you that cataracter and rugra are very very rare okay so it's better not to mention these in your exams okay so what you can see is a very hard cataract that is a brown cataract now in my video on the anatomy of lens I told you regarding the locks 3 classification okay which classifies the lens opacity is based on the nuclear color and opalescence the cortical opacities and the posterior sub capsular opacities so here in this locks classification itself you can see the progressive sclerosis of the lens initially it is you know transparent or black and then it becomes grayish then you know it becomes amber color yellowish green then changes to more yellow and then it becomes brownish in color and subsequently you are going to give the logs three classification so that's all for this video on snail cat rat I hope it was useful thank you and have a nice day