Purpose
High myopia is often characterized by a series of pathologic fundus changes. Identifying the lesions and their location is crucial in observing the progression and predicting the severity of visual impairment. We hypothesize that the closer the lesion is to the fovea, the worse the visual acuity becomes. Thus we proposed and validated a grading scheme based on potentials of macular damage
Methods
One hundred high myopic right eyes were randomly selected from our high myopia database, with 50 having best-corrected visual acuity (BCVA) ≤ 20/40(visual impairment) and another 50 having BCVA > 20/40. Two 45° images centered at fovea and optic disc of each eye were analyzed by two ophthalmologists independently. Pathologic changes in this grading scheme included myopic maculopathy, posterior staphyloma and changes of optic disc. Aided by a self-developed software, an Early Treatment Diabetic Retinopathy Study (ETDRS) grid was used to determine the location of each type of maculopathy. The maculopathy lesions and staphyloma were classified as absent, present without affecting fovea and affecting fovea area. The parameters of the optic disc were calculated by the software automatically. The inter-observer agreement of different lesions was calculated. The relationship between BCVA and the location of fundus lesions was also analyzed
Results
The mean age of the sample was 34.5±12.7 years. The mean spherical equivalence and axial length was -13.14±5.01D and 28.54 ±1.90mm, respectively. The weighted kappa values for inter-grader agreement were: 0.55 for tessellated fundus, 0.91 for diffuse chorioretinal atrophy, 0.80 for patchy chorioretinal atrophy and staphyloma, 0.57 for tilted disc, 0.61 for disc rotation, 0.78 for parapapillary atrophy and 0.68 for peripapillary intrachoroidal cavitation. Macular haemorrhage and macular atrophy were identified only in one case, respectively. The lesions of lacquer crack, Fuch’s spot were absent in this grading. In this analysis, visual impairment was related to the location of diffuse chorioretinal atrophy, patchy chorioretinal atrophy and staphyloma (all P<0.05)
Conclusions
This grading scheme proves to be a reliable assessment tool for analyzing high myopia that achieves high inter-grader agreement and gives detailed information of the lesion location, which is related to visual acuity damage