26/10/2016

Author: Sonia Gholami, Rotterdam Ophthalmic Institute

Congenital cataract [1] is prevalent with 1 to 6 cases per 10,000 births which can occur in different morphological configurations. Young adults with this type of cataract usually have a very good visual acuity and since they are exposed to this issue since birth, their vision might be compromised. However the resultant visual malfunction are sometimes inevitable and becomes especially crucial for young adults with careers which require optimal visual performance. Congenital cataract in adults may cause issues such as lack of depth perception or poor retinal development due to stimulus deprivation amblyopia [2].

In a new study we want to investigate the angular-dependency of the forward light scattering in congenital cataract eyes (known as straylight) [3][4]. Straylight is the skirt of the point spread function (PSF) and covers the outer part (θ > 1°) of it. It was reported that straylight intensity decreases greatly with θ. The same study showed that straylight parameter changes from 2.5° to 25.4° with a parabolic behavior with a minimum value around 7° in normal eyes without cataract. Recently, in one pulverulent congenital cataract subject, we observed an atypical behavior of straylight compared to what is common in age-related cataract at large angle (28°) [4][5]. Straylight decreased, whereas the small-angle behavior was normal. However it appeared that the on-set cataract had no impact on the subject’s visual acuity. We expect high level of independency between straylight and visual acuity in congenital cataract eyes. Further, we are interested to know whether the unordinary features are results of a peculiar morphology. We will evaluate the relevant optical and visual measures including intraocular straylight as well as visual acuity, contrast sensitivity and wavefront aberration (visual Strehl ratio). We also survey the morphology of the cataract using retro-illumination images. 

Figure. A ring-shape pulverulent congenital cataract observed in one subject

[1] Reddy M., Francis P., Berry V., Bhattacharya S., and Moore A (2004). Molecular Genetic Basis of Inherited Cataract and Associated Phenotype. Survey of Ophthalmology, 49(3):300-15. [2] Antonio-Santos A., Vedula S., Hatt S., and Powell C (2014). Occlusion for stimulus deprivation amblyopia. Cochrane Database of Systematic Reviews 2014, Issue 2. Art. No.: CD005136. DOI: 10.1002/14651858.CD005136.pub3. [3] Van den Berg T., Franssen L., and Coppens JE (2009). Straylight in the human eye: testing objectivity and optical character of the psychophysical measurement. Ophthalmic Physiological Optics, 29(3):345-50.[4] Vos J., and van den Berg T. (1999). Report on disability glare. CIE Collection, 135:1-9. [5] Uspeert J., de Waard P., van den Berg T., and de Jong P. (1990). The intraocular straylight function in 129 healthy volunteers; dependence on angle, age and pigmentation. Vision Research, 30(5):699-707.