a six year old boy presented with the complaint of poor vision in the left eye since six months for which he had tried treatment elsewhere . he was recommended the use of spectacle and full time patching of the right eye ( 5 days on and 1 day off ) . his reports revealed that six months back his best corrected visual acuity ( bcva ) was 20/32 in the right eye with + 4.75ds , and 20/80 in the left eye with + 5.25ds+0.5dc  85 [ fig . 1 ] . graphical presentation of monocular best corrected visual acuity ( bcva ) of the child on treatment with patching and oral levodopa . duration in months denoted on x axis , visual acuity along the y axis and the event of occlusion amblyopia is marked with stars after six months of initial therapy ( as mentioned above ) , he presented to us with the bcva of 20/25 in the right eye with + 4.5ds and 20/50 in the left eye with + 5.0ds+0.5dc  85 . , his monocular visual acuity was measured by fogging the other eye using a + 6.0ds lens . absence of a visually appreciable nystagmus and fixation switch was confirmed before recording the visual acuity . worth four dot test revealed the presence of binocular single vision for near ( 30 cm ) and distance ( 6 meters ) . we advised full time spectacle wear and 1% atropine eye drops on friday and saturday night in the right ( dominant ) eye . over four months , despite of a good compliance , there was no improvement in the vision . he was advised to continue spectacles and start patching of the right eye 6 hours / day . the parents were informed about the merits and demerits of an adjunct therapy with oral levodopa to improve compliance to patching . after taking an oral informed consent , the child after five months , when he returned for an eye examination , his bcva in the right eye was 20/80 and in the left eye was 20/22 . worth four dot test revealed suppression in the right eye for the near and distance . he was then advised to stop the right eye patching and occlude the left eye for 2 hours / day and continue levodopa . after 1 month , vision in the right eye had improved to 20/40 and that of the left eye remained stable ( 20/22 ) . after one more month , the vision in the right eye had improved to 20/32 but that of the left eye had dropped to 20/32 . levodopa and the patching were discontinued , and the parents were advised to review after 1 month . after three months , the patient returned for an eye examination when his bcva was 20/22 in each eye and stereopsis was 550 " on lang test . on the last follow up ( two and a half years after treatment with levodopa ) , bcva in each eye was 20/22 , with + 3.0ds in the right eye and + 3.5ds+0.5dc  85 in the left eye . several reports indicate that levodopa either alone or in combination with occlusion , can be useful to improve vision in the amblyopic eye . 0.5 to 2mg / kg / dose thrice a day when combined with 25% carbidopa , conversion of levodopa to dopamine is prevented in the peripheral circulation , which reduces the systemic side effects of levodopa . so far , occlusion amblyopia in patients treated with levodopa and occlusion therapy has not been reported . visual acuity gained from the treatment with oral levodopa is reported to have a high incidence of regression . however , when used as an adjunct to the occlusion therapy , levodopa can be associated with long - term improvement in the vision , and may have better compliance to patching . in india , the lowest dose available is 100 mg levodopa with 25 mg carbidopa ( tablet syndopaplus , sun pharmaceutical industries ltd , mumbai , india ) . the taste of the drug is bitter ; however , some investigators have smartly used it with a protein energy drink . we prefer the use of half a tablet 1 - 3 times / day . in this patient , half tablet three times daily turned out to be a slightly higher dose than the recommended . given that , the dose was well tolerated by the child and also there was a significant visual improvement after the commencement of oral levodopa , and hence , we continued with the same dose . although , nausea , vomiting and abdominal cramps are the most common systemic side effects seen and reported with this dose of oral levodopa , this patient had none of those , and no symptoms / signs of any other systemic toxicity . occlusion amblyopia is a rare , special form of stimulation deprivation amblyopia that is seen with the prolonged occlusion of the dominant eye , as the vision in the amblyopic eye reaches normal or near normal . however , in some children it can occur when fixation switch occurs after a shorter period of occlusion . in most cases , the amblyopia is mild and fully reversible as the fixation switches back to the initially dominant eye after stopping the occlusion , or after a few days of occlusion of the initially amblyopic eye . in most cases , however , there are rare cases in which the initially dominant eye may be left with lesser vision . levodopa , when not combined with patching / penalization , does nt cause occlusion amblyopia because both eyes are stimulated . similarly , part time patching is also not reported to cause occlusion amblyopia whether used with or without adjunctive levodopa . occlusion amblyopia is mostly reported to occur with atropine penalization specially when combined with optical penalization . in the patient reported here , occlusion amblyopia was probably due to a young age of the child and a higher dose of levodopa . both these factors together might have resulted in an increase in the plasticity of the visual cortex there by increasing the risk of an occlusion amblyopia . we humbly acknowledge the authors of a previously published paper where such a probability was anticipated . with the benefit of the hindsight , we believe , our over enthusiastic use of levodopa in this patient part time patching alone , or more parental and patient counseling to pursue full time occlusion could have been sufficient . at present , we would continue to use oral levodopa with occlusion therapy only for residual amblyopia ( if there is no improvement in the vision of the amblyopic eye after six months of a sincere attempt of patching ) . we also use combination of patching with levodopa as a primary treatment in older children ( 12 - 18 years of age ) with severe ( bcva  6/60 ) unilateral amblyopia and a poor compliance to patching . even though there is a possibility that the association of levodopa / carbidopa in this case may be casual rather than causal , we recommend that young children ( < 8 years ) on levodopa and occlusion therapy ( even if it is part time patching ) , should be more frequently followed up ( one week / year ) especially when the vision of the amblyopic eye approachs that of the better eye . this fact may also hold true for the cases on other combination of therapies , namely , patching with pharmacological penalization or optical penalization . when the inter eye acuity difference is  2 lines ( logarithm of the minimum angle of resolution - log mar ) , the duration between the follow up visits should become shorter . the parents should be warned about the possibility of occlusion amblyopia , and the need to stop levodopa and/or patching in case they are unable to return for the examination . in conclusion , it may be advisable to avoid levodopa , or use a dose of oral levodopa less than 2 mg / kg / dose three times per day when combined with patching therapy , especially , when used in younger children or for a longer duration .
part time occlusion therapy is not reported to cause occlusion ( reverse ) amblyopia . however , when combined with high dose oral levodopa , an increase in the plasticity of the visual cortex can lead to occlusion amblyopia . in this case report , we describe a six year old child who developed occlusion amblyopia following part time patching combined with oral levodopa .