The point-spread function of the eye from 0° to 100° and the pattern electroretinogram

In studies on the pattern electroretinogram the quality of the retinal image is a major concern. The use of contact lens electrodes was rejected since a good pattern could not be recorded. This is believed to be due to blurring of the retinal image. As indicator of image quality the patient's visual acuity is often used. We wondered whether this is a sufficient criterion. The retinal image is the product of the whole optical point-spread function of the eye whereas visual acuity refers only to the central portion of this function. On the basis of existing reports it can be estimated that for the young normal eye the outer edges of this function (straylight) causes considerable loss of contrast. The strength of the straylight can be much greater in older eyes. We studied the relation between the point-spread function including straylight and the pattern electroretinogram in normal eyes and some pathological cases. The measurements proved to follow the calculated contrasts on the basis of a local luminance model, with the exception of enhancement (tuning) around 60 checksize for the young normal eye. Because of the considerable differences in straylight in an older population one has to take into account that loss of pattern electroretinogram can be suffered in patients with otherwise good visual acuity.     

Does Sjogren's syndrome affect only the lacrimal gland in the eye? Time to replace the missing stones

Purpose:This study aimed to reveal the cause of meibomian gland disease and meibomian gland loss in patients with Sjögren''s syndrome (SS) as the leading factor for dry eyes.Methods:The study included a total of 30 patients with SS and dry eye symptoms and a control group of 50 age- and gender-matched healthy subjects. The dryness parameters of all the participants were evaluated. At first, meibography was performed to measure meibomian gland loss using noninvasive methods. Later, meibomian gland expression and secretion quality were evaluated using silt-lamp biomicroscopy. Correlations between the measurements were analyzed statistically.Results:In patients with SS, MG loss was significantly greater than in the control group (19.7 ± 71%, 12.7 ± 9.6%, P < 0.001). All dry eye parameters (tear film breakup time, Schirmer''s test score, OSDI, stain score, dry eye disease) were statistically significant in the SS group. There was an extremely negative correlation between upper MB loss and BUT (P = 0.08, r: 0.781). There was an extremely positive correlation between upper MB loss and staining (P = 0.015, r: 0.739). An extremely negative correlation was determined between sub-MB loss and BUT (P = 0.18, r:-0.781), and a moderately positive significant correlation was found between sub-MB loss and staining (P = 0.031, r: 0.659).Conclusion:The results of this study demonstrated that patients with SS were at a higher risk of being exposed to meibomian gland loss, which directly leads to the severe dry eye symptoms associated with SS.     

Is it safe to discharge treated proliferative diabetic retinopathy patients from the hospital eye service to a community screening programme?

Purpose

To investigate the distribution of new vessels (NV) in patients treated with pan-retinal photocoagulation for proliferative diabetic retinopathy (PDR). To assess whether it is safe to discharge treated PDR patients to the NHS Diabetic Eye Screening Programme (DESP) which uses two mydriatic 45° fields of each eye.

Methods

Consecutive treated PDR patients undergoing fundus fluorescein angiography between July 2010 and October 2011 for the purpose of looking for NV were included. The distribution of NV was mapped. In particular it was noted whether NV occurred in the area covered by the DESP standard screening images.

Results

A total of 76 patients (108 eyes) met the inclusion criteria for the study. Leaking NV were found inside the DESP fields in 89% of study patients. In 108 eyes with leaking NV, there were a total of 35 NVD and 336 NVE. NV were found within DESP fields in 83% of eyes. Of the 336 NVE, 54% occurred within and 46% outside DESP standard fields. There was no statistically significant difference in the retinal quadrant distribution of NVE.

Conclusions

If these findings apply to the whole treated PDR population, NVE would be identified in 89% of patients undergoing DESP screening. This would support stable treated PDR patients being monitored within the DESP. We found no preferential clustering of NV within quadrants or between posterior and less posterior retina suggesting that there would be no benefit to the DESP of taking an additional field or graders concentrating on one particular quadrant more than another.