Qn. 1. About Retinal nerve fiber layer defects the following is/are true.
- Retinal nerve fiber layer defects always start in the inferotemporal segment
- Retinal nerve fiber layer always starts in the superotemporal segment.
- Retinal nerve fiber layer may start in the superotemporal segment before the inferotemporal segment.
- The nasal segment RNFL loss is not of significant value in assessing glaucomatous damage.
Q. 2. Regarding clinical evaluation of the RNFL the following is/are true.
- It is best to evaluate the RNFL in an undilated pupil
- It is better to evaluate the RNFL with the direct ophthalmoscope
- RNFL should always be evaluated in red free photographs.
- A dilated pupils and the use of a 78-diopter lens may be very good for the evaluation of the RNFL
Answer: The correct answers are 3 and 4.
On occasions, one may find that superior damage is the first to occur. Therefore, the RNFL should be examined for both the superior segments and the inferior segments. The nasal segment RNFL is generally of no importance in the evaluation or in the follow up and management of glaucoma. The supero nasal and infero nasal segments are of importance in glaucoma evaluation, because they also tend to be involved in glaucomatous damage.
Answer: 4 is the correct answer.
Always try to dilate the pupils and use stereoscopic vision to evaluate the retinal nerve fiber layer defect, because there is loss of RNFL and therefore this requires stereoscopic vision to assess and determine the loss of a superficial layer of the retina. A direct ophthalmoscope provides for a restricted field of view and an undilated pupil is a challenge in assessing the optic disc and the RNFL. In Indian eyes which have more pigment, it is possible to have a good evaluation of the RNFL on colour fundus photographs of good quality.