moving on having understood clearly the etiologies of the unilateral cataracts now let us move to the bilateral Cataract and their iology now if one sees a child with bilateral cataract one needs to think about the following broad categories these are the cataracts because of genetic mutation metabolic syndromes cataracts because of chromosomal anomalies torch infection and we can also have various systemic syndromes leading to bilateral cataracts first we'll talk about the genetic mutations so genetic mutations are likely the most common cause of bilateral cataract in children okay so I want you to focus on this point they are the most common cause of bilateral cataracts in the Pediatric population and the most common inheritance is autosomal dominant followed by the autosomal recessive and then we have the XL inheritance the auto Al recessive variety is mostly seen in families with the history of consanguinity now more than 15 genes have actually been identified for the Pediatric cataracts but they mostly relate to the Cataract proteins like the crystallins and the conne which is actually a gap Junction protein now so what did we learn we learned that the most common cause of bilateral cataract is genetic mutations inherited in an autosomal dominant fashion now as they are almost never associated with a systemic problem okay now these isolated inherited congenital cataracts they actually carry a much better visual prognosis compared to those cataracts which are associated with any other ocular or systemic abnormality right so these genetic cataracts do not have any other systemic or any other local or ocular anomaly except the uh I mean they just have have the Cataract so now we are going to move on to the next ethology of bilateral Cataract and that is the metabolic cataract so we have six etiologies here that we are going to discuss so we have the galactosemia Wilson disease fabis disease Lis disease diabetic cataract hypocalcemic or parathyroid tetany related cataract so first let us talk about the galactosemic Cataract right right so as the name suggests these are the bilateral cataracts which are seen in galactosemia okay so what is galactosemia galactosemia is basically an autosomal recessive inherited congenital disease characterized by an inborn inability of the infant to metabolize galactose so they can't really process milk now the galactosemic Cataract is basically to understand that you should understand a little bit about the galactose metabolism the galactose is basically metabolized into glucose through the galactose metabolism and this galactose metabolism has three important enzymes these are the galactokinase the galactose 1 phosphate urile transfer and the galactose epimerase now an absence of any of these three enzymes involved in the conversion of this galactose to the glucose finally okay will lead to accumulation of this galactose in the blood okay now as the uh levels of galactose increase in the blood and because we do not have the enzymes of the galactose metabolism that is the galactokinase galactose one phosphate urile transferase and galactose epimerase what will happen the galactose will take an alternative pathway of metabolism and will be metabolized using this enzyme that is the Aldos reductase and leading to formation of an alcohol which is the galaco now an important point to remember about this G galactitol is that that it is an osmotic agent so when this accumulation of this galactitol in the lens what will happen it will result in an osmotic gradient increase leading to an osmotic swelling of the lens fibers because of the hydration of the lens right now galactosemia can basically be of three types so we can have type one in which there is this enzyme Galactus one phosphate UDP transferase or Ural transferase which is missing okay and then we have the type two which is because of the galactokinase deficiency and then we have type three which is because of this galactose epimerase deficiency now the one the one is the most severe type two is a milder disorder which is associated with galactosemia and cataract but it usually does not have any other systemic abnormality so that is one important point you must remember now what about the ocular manif infestations in galactosemia so the Cataract that we see in case of galactosemia is usually an anterior or a posterior subcapsular Lamar opacity at first which later on becomes nuclear and then then it'll eventually become a total cataract okay so however a typical description of cataract that is seen on retro retroillumination is that of an oil droplet cataract as you can see here now since it resembles a drop of oil so what I mean to say is if this is your capsule the initial cataract because of the lens hydration will start forming in the subcapsular region and then it comes in the nuclear area and eventually the entire lens is getting opacified so it forms the total cataract right however on retroillumination you will uh the Cataract will basically resemble a drop of oil and because of that this cataract is typically called an oil droplet cataract okay now progression of this cataract can actually be prevented and sometimes even the the some stages of the Cataract can be uh regressed they can regress also if milk and milk products are eliminated from the diet in the early stages of the disease so now we as we have discussed galactosemia let us move on to the Wilson's disease so what is Wilson disease Wilson disease basically is a inherited disorder of the copper metabolism due to the mutation in the Gene and the gene is atp7b Gene right so what happens is as the copper metabolism is affected there will be increased deposition of the copper in the liver in the basil gangon and also in your eye and this is called hepatolenticular degeneration because mainly your liver and also the lenticular structure that is your lens is actually affected now an important diagnostic feature of Wilson disease that will help you to diagnose such cataracts in these patients is increased copper levels in the blood apart from that the ceruloplasmin which is a protein that binds with the copper will actually be in decrease level in these patients so increase copper and decreased cop plasmin levels is seen in case of Wilson disease now as I told you that in Wilson disease BAS basically you will have increased copper now this increased copper is going to start depositing in various locations like in the liver in the basil gangon and in the eye now the typical size for deposition of copper in the eye is basically in the deeper parts of the cornea at the level of the Desmet membrane where it'll accumulate mostly in the peripheral area now as it accumulates in the periphery of the cornea it will give a very uh characteristic golden brown ring appear Ur and that ring is called a caser fleure ring as can be seen in the first picture similarly the copper can also deposit under the capsule of the lens and it can give a petaloid appearance okay or a um radiate a cataract which is the form of radiating fibers and apart from that this cataract will also have a brilliant Golden Green Sheen to it and because of this typical appearance in the form of Petals of a flower with a golden green color Sheen to it this type of cataract that you see in Wilson disease is called a sunflower cataract we we finished calmia we discussed about the Wilson disease also and now we are moving forward to the fabri disease so what is fabis disease fabri disease is basically an xlink lysosomal storage disorder okay so it affects the lome it is excelling and to be most specific it is xlink recessive that means it will affect the males more compared to the females now what is the deficiency here the deficiency is that of an enzyme Alpha galactose so in the liome you have this glycoprotein which is G which is represented by the gl3 over here now this glycoprotein is actually broken down by the enzyme Alpha galactose a into various smaller parts or it is basically metabolized right so if you have deficiency of this Alpha G lose cides a what will happen there will actually be an accumulation of the glycolipid in the lomes okay so that is your fabri disease so all the males with the genes basically are going to develop the disease so a pneumonic to remember various manifestation of fabri disease is shown in the slide so you can read it now here the C you have to replace the S of fabri disease with a C and C is nothing but ceramite trihexoside accumul ation ceramite Tri exocite is actually the glycoprotein 3 which gets accumulated in the lomes the first picture over here actually illustrates the angio keratomas which are actually cutaneous lesions of the capillary seen in fabri disease okay apart from that even the conjuntival vessels can show such vascular toricity and aneurysm formation and these for example here this is an aneurysm and such vessels which are showing this toricity are called screw vessels now there can also be deposition of that glycolipid three in the Cora and they can actually deposit um in the Cora in the form of a world pattern okay it's not very clear in the picture but they're going to get deposited in this Vortex pattern or World pattern and this is called Coral verticell or Vortex keratopathy okay but here what are we talking about we're basically talking about the metabolic disorders leading to a bilateral cataract right so definitely fabis disease can also lead to Cataract and the presence of bilateral cataract is almost Universal in patients of f fabis disease okay now the picture over here illustrates a wedge shape or a Spoke shaped posterior cap posterior capsular cataract so usually they will have the spoke shape cataract in case of fabis disease the next metabolic disease can which can lead to a bilateral cataract is the lowest disease the lowest disease is also called an oculo cereal syndrome it is again an excellent recessive disorder that means the males are going to be affected more the gene here is the OCR L1 Gene okay and it's basically a disorder of the amino acid metabolism now here again your brain the the neural tissue is going to get affected the kidneys are going to get affected and apart from that your eyes are going to be affected now here the basic thing we you have to remember regarding the kidneys in Lou disease is that this is a disorder of the amino acid metabolism and you will see that these patients are basically going to have Amino aciduria or proteinurea that means they're going to excrete U protein or amino acids in their urine which is also one of the diagnostic criteria to diagnose Lois disease now the classic ocular manifestation in them is actually a bilateral Cataract and the Cataract is almost Universal and they will also have microf FIA along with it apart from that they can have congenital glaucomas okay and the females who have lowest disease are mostly carriers they can also have opacities in the lens but their opacities are not going to be as severe as that of the male child having a l disease now one very important Association of L disease is with that of the posterior Len corers so I already explained to you on my my part where I was explaining you about the unilateral cataracts what is posterior lenticonus okay so posterior lenticonus can happen uh can occur as an isolated ocular anomaly or it might also be associated with Lis disease the next metabolic condition which can lead to cataract is a diabetic cataract now the diabetic cataracts are basically rare condition which typically occurs in young children or young people with type 1 diabetes mtis okay which is insulin dependent diabetes malius Now this can happen when hypoglycemia is so acute that it disturbs grossly the water balance of the body so what happens here is that or as sugar levels increases acutely that glucose instead of entering through the crep cycle or through the or through the glycolysis will also be metabolized VI the Aldos reduce pathway and this will lead to accumulation of the alcohol just like the galactitol here we have the sorbitol and this sbol will increase in the lens and as we know that solbol is basically a high osmotic agent as the amount of sbol increases in the lens it will cause increase osmotic gradient within the lens and because of which the water will enter inside the lens leading to hydration this hydration can actually be seen in the for in the form of vacuum formation and swelling of the lens and ultimately there will be opacification and cataract formation so a large number of fluid vacuum are actually going to appear okay in that hydrated lens and it basically appears in the anterior and the posterior part of the capsule and as you can see the lens get hydrated now because of the increased hydration what happens is that the curvature of the lens increases and therefore they are going to come with myopia right as we know that in myopia basically the lens curvature is more and therefore as the curvature increases the power of the lens increases and therefore the image is going to be focused in front of the retina right Sim similarly in true diabetic cataract when the lens hydration occurs acutely there's an increase in the power of the lens and therefore these patients are going to come to you with change in their refract uh refraction or change in the prescription and usually what you're going to find is a presence of myopia so that might be your initial uh symptom or sign that you see in these patients now the lens because of that hydration will become cataractous and it will develop these dense white subcapsular opacities in the anterior and the posterior cortex and these dense white opacities that you see in the anterior and posterior cortex will actually resemble a snow storm and therefore this type of cataract that you see in diabetes is called diabetic snowflake cataract or a snowstorm cataract now the first image illustrates the snowflake cataract where the second one basically depicts the intence due to the acute lens hydration now remember all these character istic appearances that we are discussing they may be seen early on but ultimately all cataracts get mature and it might not be possible for us to differentiate them just by their morphology the last metabolic condition that can lead to cataract is an hypocalcemic condition the hypocalcemia or a parathyroid tetany it basically occurs when there's atrophy of the parathyroid glands or sometimes after a thyroidectomy operation when the parathyroids might be removed along with the thyroid this will lead to hypocalcemia now calcium levels in the Aquis are very important to maintain the health of the lens and particularly the membrane of the lens as there's hypoglycemia the membrane of the lens will basically get affected and this will also affect the various transport that is occurring across the membrane of the lens as a result the sodium concentration within the lens will increase and we know that wherever there is sodium there's also going to be water so as the sodium concentration increases inside the lens the water content also will will increase inside the lens leading to hydration and ultimately you will have cataract now it's trivia time so I want you to answer in the comment section that in which infection do we see snowflake opacities in the cornner be very careful what we discussed here is about the snowflake cataract now I want you to answer that in which infection do we see snowflake opacities occurring in the cornea as well here [Music] we I'm [Music] in