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Low Vision Assessment and Rehabilitation

Laser Treatment

Laser treatments are on an outpatient basis. Both eyes were dilated and examined by the vitreoretinal specialist. Only one eye is treated at a visit because of the short-lived visual decline that can sometimes occur immediately after laser treatment. Treatments for macular edema are usually controlled by referring to the fluorescein angiography findings.

Macular laser treatments are painless, but require significant patient cooperation. Panretinal laser treatments for proliferative diabetic retinopathy (PDR) can sometimes cause modest, brief discomfort. The temporary control of eye movements and avoidance of pain can be achieved by injections of local anesthetics under the eye, but this is only occasionally necessary.

The two different kinds of laser treatment (grid--for diabetic macular edema, and panretinal--for proliferative diabetic retinopathy) are given using the same laser instrument with the patient sitting, leaning forward with his/her head in a chin rest, and with the forehead supported, just as in a routine eye examination. The treatments may vary in length from a few minutes to half an hour for extensive laser applications. Patients undergoing retinal laser treatment should have someone to drive them home. There are usually no physical restrictions following laser treatment. If the patient uses anticoagulants, he should tell this to the ophthalmologist before the laser treatments, but it is rarely necessary to stop them.

Below are two charts showing the laser treatments: one was to treat the patient's diabetic macular edema, and the other was to treat the patient's proliferative diabetic retinopathy.

Key: µ = micrometer; PRP=panretinal laser photocoagulation

Macular Grid Laser Treatments

Grid laser treatments are applied in a checkerboard pattern to patients with diffuse macular edema avoiding the very center of the vision. Laser treatments in macular edema are spaced over time because it takes 6 to 8 weeks to assess the results of treatment. Fluorescein angiograms are taken at intervals for patients with severe macular edema. Retreatments are indicated because of the retention or redevelopment of areas of foveal retinal thickening involving the "center of the vision."

The gradual improvement of Dr. Cole's visual acuity OD [right eye] occurred over many months following the completion of his macular treatment OD. The visual acuity OS [left eye] failed to improve significantly despite control of the macular edema owing to irreparable diabetic damage. Lesser degrees of macular edema are often treated by focal applications of laser directly to visible microaneurysms, which are tiny vascular dilations.

Panretinal Laser Photocoagulation (PRP)

PRP is the application of an extensive laser scatter pattern using large laser spots outside the center of vision, and principally in the retinal midperiphery, where the diabetic damage to retinal blood vessels is most severe. The amount of laser treatments required to control proliferative diabetic retinopathy varies with the degree of retinal damage, the disappearance of abnormal retinal new vessel proliferations, the control of intraocular scar tissue formation, and avoidance of intraocular hemorrhaging.

In Dr. Cole's case, the long travel distance, the time constraints of his professional practice, as well as requirements for vision rehabilitation training, curtailed his availability for laser treatment and extended the time of his laser treatments.