Scotopic and photopic dissociation in patients with chronic central serous chorioretinopathy

Abstract

 

Purpose

 

Central serous chorioretinopathy (CSC) is a common retinal cause of vision loss. It is characterized by serous detachment of the neurosensory retina, caused by one or several lesions in the retinal pigment epithelium (RPE). Common symptoms include blurred vision with a central scotoma, metamorphopsia, micropsia, dyschromatopsia, hypermetropization and reduced contrast sensitivity. A minority of patients develop chronic CSC, which may present with so-called “gravitational tracts” - vertical patches of RPE hypopigmentation, frequently also with outer retinal atrophy. The objective of this study was to assess the effect that these lesions have on rod and cone function, respectively.

 

Methods

 

13 patients were recruited from the National Eye Clinic at Glostrup Hospital, Denmark. Inclusion criteria were chronic CSC with no active episodes since at least six months and tract lesions visible on spectral domain optical coherence tomography (SD-OCT). Exclusion criteria were inability to focus at the target circle during microperimetric examination and concurrent eye disease. Patients had their best-corrected visual acuity measured by Snellen standards. Microperimetry under scotopic and photopic conditions was performed after dilation and adaptation. To verify the location of the gravitational tract lesion, SD-OCT was performed. Microperimetric results were projected onto the SD-OCT images and outer retinal thickness was measured for each test point.

 

Results

 

Mean scotopic microperimetry in tract areas was 0,63 dB (95% CI 0,16 - 1,10 dB), compared to 3,8 dB (95% CI 3,05 - 4,59 dB) in normal areas. Mean photopic microperimetry in tract areas was 9,8 dB (95% CI 7,26 - 12,4 dB), compared to 15,5 dB (95% CI 13,8 - 17,2 dB) in normal areas.

 

Conclusions

 

In patients with chronic central serous chorioretinopathy and gravitational tracts, rod function is more severely disrupted than cone function. This has interesting implications in the understanding of photoreceptor properties, suggesting that the pathway of cone survival is different from that of rod survival.

 

 

Photopic microperimetry showing relative scotoma over tract lesions at 3 and 4 o'clock.

 

 

Scotopic microperimetry showing absolute scotoma over tract lesions at 3 and 4 o'clock.

 

Keywords: 688 retina • 648 photoreceptors • 585 macula/fovea