The differences in form and height of dome-shaped maculas seem to be unevenly associated with vision-threatening conditions. Dome-shaped maculas with high bulges seem to present with more severe pigmented epithelium atrophic changes and are commonly associated with serous retinal detachment. However, it remains unknown whether smaller bulges demonstrate the same evolution. A study based in France recently determined that bulges smaller than 100µm are characterized by slower evolution, better visual prognosis and fewer complications compared with classic dome-shaped macula. Macular bulge increase was also associated with eye elongation and thinning of the peripheral choroid.

The study assessed 58 eyes of 33 patients with dome-shaped macula—32 (55%) were classified as classic (bulge greater than 100µm) and 26 (45%) as mini (bulge less than 100µm).

During the mean follow-up period of 51.76 months, mean axial length (AL) increased from 26.99mm to 27.12mm and mean macular bulge height increased from 235.88μm to 262.34μm. Bulge height change was significantly higher than axial length change. Mean peripheral choroidal thickness significantly decreased nasally, temporally and inferiorly. The eyes in the mini group exhibited shorter AL (26.17mm vs. 27.66 mm), greater visual acuity (0.169logMAR vs. 0.437logMAR) and fewer macular complications compared with the classic group.

The researchers found that the small increase in AL compared with the high bulge increase supports the fact that eye elongation is more pronounced around the bulge than at the top of it. “This may suggest that dome-shaped macula is not due to an inward progressive bulging of the macular area but rather to a differential elongation of the eye predominant in the perimacular region,” they concluded in their paper.