When we examine patients, we are looking at their eyes and their pathologies from the outside seeing in. We can get some idea as to the visual obscuration caused by a cataract by seeing how our view of the retina is distorted when looking through it. But this may not accurately reflect what the patient actually sees. With retinal disease it is even more difficult to understand what visual symptoms are seen by the patient for a specific retinal disease process.
Some famous artists were known to have ocular pathology: Claude Monet suffered from cataracts and Edgar Degas likely had a form of macular degeneration. These conditions very significantly affected the work of these artists and when looking at a time line of their work, we can see progressive deterioration of details, colors, and forms.
Recently, I had two patients who have experience in graphic arts and computer simulations and each made me photographs to show the effect of their ocular condition. The first patient had moderate nuclear cataracts which decreased her visual acuity to 20/50. What is most striking is that measuring Snellen letters, which are high contrast and monochrome, does not accurately reflect the full decline in the patient’s vision. The most noticeable change is the color spectrum and the transmission of certain hues, particularly blues and whites.
In the before and after photos (Figure 1) the contrast is also improved with a greater separation between light and dark. The patient also subjectively reports that she now uses less light in her home to do the same tasks and that in particularly challenging situations, such as walking into a dark room at night, she is now able to see sufficiently to navigate.
Since the effect of the cataract is so much more than just Snellen acuity, should we be doing other types of pre-operative testing to determine visual impairment? While some use an arbitrary cut-off such as 20/50 vision or worse to determine the need for cataract surgery, these patient-generated figures suggest that we should look at functional visual needs such as contrast and colors as well.
The effect of retinal disease on the patient’s vision can be more challenging to understand than that of cataracts. In the case presented here, a healthy 45 year old patient with no past medical or ocular history presented with a complaint of seeing a persistent lightning bolt in part of the vision with some slight smearing in a few spots of his central vision. He still read 20/20 on the Snellen chart.
Examination showed an impending central retinal vein occlusion (Figure 2A) with tortuous vessels and a slowed vascular transit time as seen on fluorescein angiography. As the disease process progressed into a partial central retinal vein occlusion the patient noted more symptoms: more prominence to the lightning bolt shapes (which correspond to retinal vasculature) as well as deterioration of the central vision to 20/25 (figure 2B) and then to 20/40 (figure 2C) as macular edema set in.
This patient was fortunate that the vein occlusion and macular edema resolved quickly without the need for intra-vitreal injections. But even after 8 weeks of healing there are still some persistent visual changes such as splotchy patches and diminished contrast even though the Snellen acuity returned to 20/20.
Studying these patient-made simulations helps us to understand what the patients are actually seeing with various ocular pathologies.
All content is © 2018 by Uday Devgan MD. All rights reserved.