Abstract
Purpose::
Decrease in visual acuity due to Macular Hole (MH) has been demonstrated to depend on MH diameter. In addition, acuity outcome after MH surgery is considered to partially depend on the size of a MH before treatment. The most common measure of MH size is its diameter. The present study investigated whether 1- or 3- dimensional estimates of MH parameters on Optical Coherence Tomography (OCT) would be more highly correlated with pre-operative acuity impairment. The same pre-operative structural measures were then evaluated in predicting post-operative functional outcome after 1-3 as well as 6 or more months.
Methods::
Visual Acuity (logMAR on ETDRS chart) and OCT3 scans were taken in 24 consecutive patients (age 60 to 82) with idiopathic MH. Acuities were only included when no signs of cataract were noticable. OCT images were analyzed by three independent researchers, using manually placed caliper markers. Structural measures were 1-dimesional in microns: base diameter (a), hole height (b), minimum diameter, and MH index (ratio of a/b, as per Kusuhara et al., 2004, Am J Ophth, 138:709-716), and 3-dimensional estimates of the volume of the affected retinal area [V = π (a/2)2b] with and without the central gap.
Results::
Pearson’s correlations coefficients indicated that pre-operative acuity was most closely related to minimum MH diameter (r = .78, p < .01) and was significantly correlated with all other structural measures, except MH height (r = .001). At 1-3 months, only minimum diameter remained a significant predictor of visual acuity (r = .69, p < .01), while none of the structural parameters were significantly correlated with acuity after 6 or more months.
Conclusions::
The results indicate that structural characteristics of a MH can indicate the functional outcome of MH surgery only in the short term. After 6 or more months, however, acuity recovery continues to improve (90% of participants recovered acuity of 20/50 or better), independently of the level of preoperative damage to the macula. While central MH diameter was highly correlated with acuity pre- as well as post-surgically, 3-dimensional MH characteristics were not statistically more accurate in estimating acuity outcome.
Keywords: visual acuity • macular holes • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)