Hyperpigmented epiretinal membrane in macular telangiectasia type 2: imaging characteristics and correlation with transretinal pigment migration

Vitreomacular interface abnormalities in type 2 macular telangiectasia (MacTel)

PURPOSE

To describe the different types of vitreomacular interface abnormalities (VMIA) seen on optical coherence tomography (OCT) in type 2 macular telangiectasia (MacTel) and explain the possible reasons for its development.

METHODS

In this retrospective cross-sectional study, type 2 MacTel eyes with macular volumetric OCT imaging protocol were included to identify different types of VMIA such as abnormal PVD, vitreomacular traction (VMT), ERM, and lamellar and full-thickness macular hole. The VMIA findings were then correlated with different MacTel disease stages and visual acuity.

RESULTS

One thousand forty-three OCTs of 332 type 2 MacTel eyes from 169 patients at different visits were examined. VMIA was detected in 709 (68%) of those OCT scans in 216 (65%) eyes. There were 273 (39%), 31 (4%), 89 (13%), 7 (1%), and 381 (54%) OCT scans with vitreomacular adhesion, VMT, ERM, and inner and outer lamellar macular holes discovered respectively. VMIA eyes had a high frequency of abnormal PVD (p = 0.001) and retinal pigment clumps (RPCs) [p = 0.032]. Eyes with abnormal PVD (p = 0.034) and RPC (p = 0.000) had a higher rate of ERM development. RPC was linked to an increased risk of developing ERM (odd ratio 2.472; 95% CI 1.488-4.052). RPC and ERM contributed significantly to poor visual acuity (0.661 ± 0.416, 20/92).

CONCLUSION

OCT reveals a high frequency of VMIA in advanced type 2 MacTel eyes. RPC could be responsible for the development of anomalous PVD, as well as subsequent VMIAs and ERM. Additional work is required to examine the long-term changes and surgical outcomes of these eyes.

Model of zonular forces on the lens capsule during accommodation

How the human eye focuses for near; i.e. accommodates, is still being evaluated after more than 165 years. The mechanism of accommodation is essential for understanding the etiology and potential treatments for myopia, glaucoma and presbyopia. Presbyopia affects 100% of the population in the fifth decade of life. The lens is encased in a semi-elastic capsule with attached ligaments called zonules that mediate ciliary muscle forces to alter lens shape. The zonules are attached at the lens capsule equator. The fundamental issue is whether during accommodation all the zonules relax causing the central and peripheral lens surfaces to steepen, or the equatorial zonules are under increased tension while the anterior and posterior zonules relax causing the lens surface to peripherally flatten and centrally steepen while maintaining lens stability. Here we show with a balloon capsule zonular force model that increased equatorial zonular tension with relaxation of the anterior and posterior zonules replicates the topographical changes observed during in vivo rhesus and human accommodation of the lens capsule without lens stroma. The zonular forces required to simulate lens capsule configuration during in vivo accommodation are inconsistent with the general belief that all the zonules relax during accommodation.