In vivo confocal microscopy findings in central toxic keratopathy

Central toxic keratopathy is an uncommon complication after laser in situ keratomileusis. We report the confocal microscopy findings in a case of central toxic keratopathy that confirm loss of keratocytes from the corneal stromal bed in the acute phase, with gradual repopulation over the following year.     

Is myopia a protective factor against central serous chorioretinopathy?

AIM: To evaluate if any association exists between central serous chorioretinopathy (CSCR) and the refractive status of the eye. METHODS: This retrospective, institutional, case control study included 499 patients, wherein 262 patients diagnosed as acute CSCR, were compared with an age and gender matched control group of 237 patients. All patients were evaluated with a detailed systemic and ocular history, objective and subjective refractions for both eyes and complete ocular examination by a retina specialist, at all visits. Optical coherence tomography confirmed the diagnosis of CSCR. RESULTS: The mean age was found to be 40±7y in the study group (Group 1) compared to 38±10y in the control group (Group 2). Most common refractive status in the study group, was emmetropia seen in 191 patients (72.9%), followed by hypermetropia seen in 47 patients (17.9%) and astigmatism seen in 21 patients (8.0%). Only 3 subjects (1.1%) had myopia, which was less than or equal to 1.0 D, compared to 70 subjects (29.5%) in the control group, suggesting a statistically significant lower incidence of CSCR among the myopic patients (P< 0.0001). With respect to the systemic factors, 26 (9.9%) patients were using systemic steroids in the study group (Group 1) compared to none in the control group (Group 2) suggesting a statistically significant association of CSCR with systemic steroid use (P<0.05). No other significant systemic risk factors were noted. CONCLUSION: Though CSCR is a multifactorial disease, myopia serves as a protective factor for CSCR. Thus, myopic eyes are less likely to develop CSCR. Since both retinal pigment epithelium (RPE) and choriocapillaris are postulated in the pathogenesis of CSCR, chorio-retinal thinning and atrophy seen in myopic eyes are less likely to cause CSCR.     

Is word recognition different in central and peripheral vision?

Peripheral vision plays an important role in normal reading, but its role becomes larger for visually impaired people with central-field loss. This experiment studied whether lexical processing differs in central and peripheral vision through the analysis of word-frequency effects in lexical decisions. We asked two main questions: (1) Do central and peripheral vision differ in the time course of lexical processing? and (2) do central and peripheral vision differ in the quality of lexical processing? To address the first question, we examined the time course of frequency effects in central and peripheral vision over a range from 25 to 500 ms. We found that significant frequency effects occurred for the shortest exposures, 25-50 ms, in central vision, whereas significant frequency effects did not occur in peripheral vision until 100 ms. To address the second question, we used word-frequency effects as a marker for the nature of lexical processing. We compared frequency effects in central and peripheral vision for data within matched ranges of percent accuracy (0-20%, 20-40%, 40-60%, 60-80%, and 80-100%). We found that there was no difference in the pattern of frequency effects in central and peripheral vision at equivalent performance levels. We conclude that lexical processing is slower in peripheral vision, but the quality of lexical processing is similar in central and peripheral vision.