Preoperative visual acuity as a prognostic indicator for laser treatment of macular edema due to branch retinal vein occlusion

Association between photoreceptor integrity and visual outcome in diabetic macular edema

PURPOSE

To investigate the correlation between foveal photoreceptor integrity and final visual acuity (VA) after treatment of eyes with diabetic macular edema (DME), and to determine the visual prognostic factors.

METHODS

We retrospectively studied 61 eyes of 52 patients with DME who were treated successfully with intravitreal triamcinolone injection (IVTA). Using spectral domain optical coherence tomography (SD-OCT), the eyes were categorized into three groups at the final visit according to restoration of the photoreceptor inner and outer segment junction (IS/OS) and the external limiting membrane (ELM): (1) the A group, with a completely visible IS/OS and ELM, (2) the B group, with a disrupted IS/OS and intact ELM, and (3) the C group, with a disrupted or loss of the IS/OS and ELM. Disrupted IS/OS length (DIL), disrupted ELM length (DEL), and mean disrupted IS/OS and ELM length (DIEL) were measured at the initial and final visits. Foveal thickness (FT), macular center thickness (MCT), and outer nuclear layer (ONL) thickness were also measured at the initial and final visits. Multivariate analysis testing was performed over the measured SD OCT variables.

RESULTS

Final VA was closely associated with IS/OS integrity at the final visit; final VA (logMAR) in the A group (0.21 ± 0.14; 31 eyes) or B group (0.31 ± 0.21; 15 eyes) was significantly better than that in the C group (0.45 ± 0.33; 15 eyes) (p < 0.001). Shorter DIL, DEL, and DIEL at the final visit were associated with better final VA. Multivariate analysis showed that DIEL (r = 0.564) have the greatest correlation coefficient with final VA compared to DIL (r = 0.561) and DEL (r = 0.540). Better VA, preservation of the IS/OS and ELM at the initial visit were associated with intact photoreceptor integrity after resolution of DME. However, MCT, FT, and ONL thickness had no significant correlation with photoreceptor integrity.

CONCLUSION

IS/OS and ELM are useful hallmarks for use in evaluation of foveal photoreceptor layer integrity, and are closely associated with final VA in DME. Pretreatment VA and photoreceptor status can predict potential restoration of photoreceptor integrity and subsequent visual recovery in DME.

Association between integrity of foveal photoreceptor layer and visual outcome in retinal vein occlusion

PURPOSE

To investigate the correlation between integrity of foveal photoreceptor layer and initial as well as final visual acuity (VA) after successful resolution of macular oedema (ME) associated with retinal vein occlusion (RVO).

METHODS

We retrospectively studied 31 eyes of 31 patients with resolved ME secondary to RVO. The integrity of foveal photoreceptor layer was studied using the junction between photoreceptor inner and outer segment (IS/OS) on spectral domain optical coherence tomography (SD OCT). The study eyes were categorized into three groups at final visit; V group with completely visible IS/OS, P group with partially detected IS/OS and I group with invisible IS/OS. Disrupted length of IS/OS and external limiting membrane (ELM) were measured.

RESULTS

Final VA (logMAR) was closely associated with the IS/OS integrity at final visit; final VA in V group (0.03 ± 0.05) was better than that in P group (0.21 ± 0.23) (p = 0.027) and final VA in P group was better than that in I group (0.70 ± 0.36) (p = 0.004). Better initial VA (logMAR) and shorter length of disrupted IS/OS at initial visit were closely associated with better final VA (logMAR). In addition, final VA (logMAR) was closely associated with the length of disrupted IS/OS and ELM at final visit.

CONCLUSIONS

  After resolution of ME associated with RVO, the final VA is associated with the integrity of foveal photoreceptor layer. Better VA and the smaller length of disrupted IS/OS on SD OCT at initial visit are indicators of better visual outcome in patients with RVO.

Branch retinal vein occlusion: pathogenesis, visual prognosis, and treatment modalities

In branch retinal vein occlusion (BRVO), abnormal arteriovenous crossing with vein compression, degenerative changes of the vessel wall and abnormal hematological factors constitute the primary mechanism of vessel occlusion. In general, BRVO has a good prognosis: 50-60% of eyes are reported to have a final visual acuity (VA) of 20/40 or better even without treatment. One important prognostic factor for final VA appears to be the initial VA. Grid laser photocoagulation is an established treatment for macular edema in a particular group of patients with BRVO, while promising results for this condition are shown by intravitreal application of steroids or new vascular endothelial growth factor inhibitors. Vitrectomy with or without arteriovenous sheathotomy combined with removal of the internal limiting membrane may improve vision in eyes with macular edema which are unresponsive to or ineligible for laser treatment.