Slit beam enhances visualization with corneal opacities
A tool found in every ophthalmologist’s office, the slit beam, can also be used to enhance visualization during cataract surgery in patients who have corneal opacities.
Reviewed by Mahmoud F. Rateb, MD
Assiut, Egypt-A slit beam mounted on a surgical microscope can enhance visualization during cataract surgery, particularly in patients with corneal opacification, according to Mahmoud F. Rateb, MD.
Dr. Mahmoud uses the slit beam diaphragm of the surgical microscope (Haag Streit HS-Hi-R NEO 900) to identify important structures, such as the anterior capsule, nucleus, cortical matter, and posterior capsule.
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“I found that when I examined patients with corneal opacities and cataracts with the slit beam I could see details inside the eye better, such as the anterior capsule, the nucleus, and sometimes other minute details,” said Dr. Mahmoud, lecturer and consultant of ophthalmology, Assiut University Hospital, Egypt.
“But when I tried to use a surgical microscope in the operating room during procedures, I literally saw nothing. It was very difficult to see anything inside the eye,” he said, explaining why he developed the new technique, adapting a common examination tool for complex surgeries.
Overcoming barrier
The barrier he wanted to overcome stems from the difference between the diffused coaxial light in the microscope and the lighting in the slit beam. When Dr. Rateb began performing cataract surgery under the slit beam, he found that this eliminated the glare from scatter produced by the irregular corneal lamellae characteristic of corneal opacities.
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As Dr. Rateb fine-tuned the technique, he learned from surgical technicians that he could adjust the direction and angle of the light, which also improved visualization.
Dr. Rateb noted that about 20% of his patients have severe corneal opacities associated with the high prevalence of trachoma in Egypt. These patients may be simultaneously placed on waiting lists for both cataract surgery and keratoplasty but may not be scheduled for the corneal transplant for years. In the interim, many will need cataract surgery to improve their visual acuity.
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