Lasers in Ophthalmology

Ophthalmic lasers are presently used clinically for both diagnostic and therapeutic purposes. 

Diagnostic lasers are based on a principle called optical coherence and are used to diagnose diseases of the retina, optic nerve and cornea and to calculate the power of the intraocular lens to be placed during cataract surgery. Laser interferometry is now mandatory for power calculation in accommodative intraocular lenses used for presbyopic correction. 

We and some others have been using in wave-front guided LASIK, an aberrometer is used to calculate pre-existing errors in the human eye using a collimated laser beam. We observed that Wave-front guided LASIK increased visual acuity and contrast sensitivity in more than 70% of patients and 50% of the patients obtained more than 20/20 vision. Femtosecond laser technology is now being used to make precise corneal incisions for both lasik and in corneal transplant surgery.

Therapeutic lasers use a large portion of the electromagnetic spectrum ranging from the ultraviolet portion through the visible wavelengths and into the near and far infrared areas. The interaction of specific laser emission of different wavelengths with various ocular tissues causes distinctly different tissue changes, which include laser photocoagulation, photodynamic therapy, photovaporization, photodisruption and photoablation.

Laser photocoagulation using the Argon or frequency doubled YAG laser, is most widely used in the management of diabetic retinopathy. We observed that in large clinical trials timely photocoagulation can prevent blindness in more than 90% of diabetics, and is playing a major role in preventing blindness among the millions of diabetics in India. 

Laser photodynamic therapy, done in conjunction with intraocular injection, has completely revolutionized the management of macular degeneration. Clinical trials show that it stabilizes or improves vision on more than 80% of patients with age-related macular degeneration. 

In our studies involving 150 patients we observed that collagen cross-linking using an ultraviolet laser light prevents progression of Keratoconus in 100% of the patients where a progressive thinning of the cornea leading to severe decrease in vision.

The presentation will include some of our experiences with this new technology in bringing benefits to the patients.