Visual acuity loss associated with excessive "dry macula" in exudative age-related macular degeneration

Abstract

Purpose: To investigate the correlation between visual acuity and central macular thickness (CMT) and choroidal thickness (CCT) in patients with wet age-related macular degeneration (AMD).

Methods: In this retrospective analysis, 14 eyes that received >10 ranibizumab injections (based on pro re nata [PRN] regimen) and maintained initial visual acuity gain were analyzed. The following 5 parameters were measured at the foveal center: CMT (distance from the inner limiting membrane [ILM] to Bruch's membrane); central retinal thickness (CRT; distance from the ILM to the inner limit of the retinal pigment epithelium or subretinal fluid [SRF]); SRF thickness (SRFT); pigment epithelium detachment thickness (PEDT); and CCT. The correlation between the logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) and the 5 parameters was examined with generalized estimating equations.

Results: CMT, CRT, and CCT were negatively correlated with logMAR BCVA (P=0.031, 0.023, and 0.036, respectively) when only CMT values less than the thickness that maximized visual acuity for each eye were used for the analysis. Each 100-μm reduction in CMT, CRT, or CCT improved logMAR BCVA by -0.1, -0.08, or -0.07, respectively. SRFT and PEDT were not correlated with BCVA. The median CMT that maximized the visual acuity was 230 μm.

Conclusion: Dry macula with CMT <230 μm was associated with temporary decrease in visual acuity in AMD patients whose visual acuity was maintained with PRN regimen.

Keywords: age-related macular degeneration; dry macula; intravitreal injections; ranibizumab; visual acuity.

Figure 1

Regression quadratic functions of the relationship between CMT and visual acuity in representative cases. Notes: (A) A 71-year-old woman with PCV was examined 26 times and received 15 ranibizumab injections over a period of 29 months from initial examination. With a linear coefficient of 0, quadratic approximation gave the following BCVA: BCVA =−0.0446+3.29e−6*(CMT −312)^2. The best BCVA in this patient was logMAR −0.0792, and the best CMT (mean CMT from 12 examinations with this visual acuity) was 284 μm. (B) A 71-year-old man with type 1 CNV. (C) A 72-year-old man with PCV. (D) A 76-year-old man with type 1 CNV. (E) An 80-year-old woman with PCV. (F) An 81-year-old man with PCV. (G) An 84-year-old man with PCV. (H) A 92-year-old woman with PCV. (I) An 84-year-old woman with PCV. (J) A 72-year-old woman with type 1 CNV. (K) A 67-year-old man with type 2 CNV. (L) A 78-year-old man with type 1 CNV. (M) A 79-year-old man with PCV. (N) A 72-year-old man with PCV. Abbreviations: CMT, central macular thickness; PCV, polypoidal choroidal vasculopathy; BCVA, best-corrected visual acuity; CNV, choroidal neovascularization; logMAR, logarithm of the minimum angle of resolution.

Figure 2

Optical coherence tomography of the 71-year-old woman with polypoidal choroidal vasculopathy. Notes: (A) Seven months after initial intravitreal injections of ranibizumab, logMAR BCVA was 0 and CMT was 251 μm. (B) Ten months after initial intravitreal injections of ranibizumab, logMAR BCVA was −0.079 and CMT was 291 μm. (C) Fourteen months after initial intravitreal injections of ranibizumab, logMAR BCVA was logMAR −0.041 and CMT was 381 μm. Abbreviations: logMAR, logarithm of the minimum angle of resolution; BCVA, best-corrected visual acuity; CMT, central macular thickness.

Figure 3

Long-term visual acuity prognosis of all 14 patients. Notes: Prognosis was (A) longer in half of the patients and (B) shorter in half of the patients. Visual acuity prognosis was stable in most of the patients. Abbreviation: logMAR, logarithm of the minimum angle of resolution.