Visual performance and cataract morphology:
The nexus between subjective and objective measures of visual function
Visual acuity (VA) testing is the most widely used and accepted method of determining visual functioning and hence need for surgery in the cataractous patient. The limitations of VA testing are well known, and the need to explore the patient's subjective visual disability (VD) is widely appreciated. However, linking the subjective and objective findings to develop a management plan can be difficult. We present three typical cases representing the different cataract morphologies, all with 6/9.5 logMAR acuities but with different contrast sensitivity (CS), glare sensitivity, color vision and VD findings. We discuss the effects of cataract morphology on visual function and how the various methods of visual assessment can help determine the true degree of visual impairment.
Table 1: Activities listed in the visual disability assessment
|
|
High contrast (HC)VA |
Low contrast (LC)VA |
LCVA with glare |
|
|
Snellan (logMAR) |
Snellan (logMAR) |
Snellan (logMAR) |
|
|
1 cortical |
6/9.5 (0.2) |
6/10.0 (0.22) |
6/20.0 (0.53) |
|
2 nuclear |
6/9.5 (0.2) |
6/14.0 (0.37) |
6/23.0 (0.58) |
|
3 PSC |
6/9.5 (0.2) |
6/13.0 (0.34) |
6/90.0 (1.19) |
Table 2: High contrast (HCVA), low contrast (LCVA) and low contrast with glare visual acuities for the three patients. Nuclear cataract gives the greatest reduction in LCVA and the least reduction in LCVA in the presence of glare. Cortical cataract gives the smallest reduction in LCVA and posterior subcopsular cataract gives the greatest reduction in LCVA in the presence of glare.
Published in full in:
Asia-Pacific Journal of Ophthalmology, October 1994: Vol 6 No 4; 12-18.
Konrad,Pesudovs*,
Douglas J Coster**
* PhD student, Consultant Optometrist, Dept of Ophthalmology, Flinders Medical Centre
** Lions Professor of Ophthalmology, Flinders Medical Centre
Index of Papers
[ Welcome ][ Publications ]