Delayed recovery of the optical Stiles-Crawford effect in a case of central serous chorioretinopathy

Measurement of the photoreceptor pointing in the living chick eye

The chick eye is used in the study of ocular growth and emmetropization; however optical aberrations in the lens and cornea limit the ability to visualize fine retinal structure in living eyes. These aberrations can be corrected using adaptive optics (AO) allowing for cellular level imaging in vivo. Here, this capability is extended to measure the angular tuning properties of individual photoreceptors. The left eyes from two White Leghorn chicks (Gallus gallus domesticus) labeled chick A and chick B, were imaged using an AO flood illuminated fundus camera. By translating the entrance pupil position, the same retinal location was illuminated with light of varying angles allowing for the measurement of individual photoreceptor pointing. At 30° nasal from the pecten tip, the pointing direction for both chicks was towards the pupil center with a narrow distribution. These particular chicks were found to have a temporal (T) and inferior (I) bias in the alignment with peak positions of (0.81 T, 0.23 I) and (0.57 T, 0.18 I) mm from the pupil center for chicks A and B respectively. The rho, ρ, values for the major, ρL, and minor, ρs, axes were 0.14 and 0.17mm(-2) for chick A and 0.09 and 0.20mm(-2) for chick B. The small disarray in the alignment of the chick photoreceptors implies that the photoreceptors are aligned to optimize the light entering the eye through the central portion of the pupil aperture. The ability to measure pointing properties of individual photoreceptors will have application in the study of eye growth and various retinal disorders.

Retinal thickness change in relation to visual acuity improvement after 23-gauge vitrectomy for idiopathic epimacular membrane

PURPOSE

To assess the course of macular thickness change in relation to visual acuity improvement, in patients being operated for idiopathic epimacular membrane by 23-gauge pars plana vitrectomy.

MATERIALS AND METHODS

The clinical charts of 21 eyes of 19 consecutive patients (9 male and 10 female) were assessed retrospectively. Postoperatively, patients were followed up by best-corrected Snellen visual acuity (BCVA), a thorough ophthalmological examination, including fundoscopy, retinal thickness, and macular morphology as demonstrated by optical coherence tomography. The main outcome measures of the study were changed in central macular thickness (CMT)and visual acuity during the follow-up period.

RESULTS

The mean duration of follow-up was 15.9 ± 1.0 months (range 12-24 months). Mean baseline BCVA improved from 0.22 ± 0.03 (decimal fraction) to 0.50 ± 0.07 at the last visit (P = 0.001), whereas baseline CMT (408 μm) decreased to 283 μm at final examination (P = 0.001). During the follow-up, 10 eyes (47%) achieved 0.5 or better BCVA. The first significantly lower CMT readings were obtained at third-month visit while BCVA showed an improvement with the significant difference following 9 months after the surgery. In total, 8 out of 11 phakic eyes underwent cataract extraction with a mean of 6.8 months (range 1-12 months).

CONCLUSIONS

After a successful epimacular membrane removal, functional recovery takes at least 9 months in comparison to much early resolution in macular oedema that was evident at third month following the surgery.