Iris, Sclera & Eyelid Transillumination Uses
Normal Iris: Transillumination of a normal iris shows a radial pattern with the sphincter muscle as a darker area around the pupil. Usually a shadow of the lens can be seen. Darker color eyes have more pigment than blue eyes. Aperature adjustment is often necessary for proper image exposure.
PDS: Pigment Dispersion Syndrome as seen in pigmentary dispersion is a type of open angle glaucoma caused by pigment graules gradually breaking free from the iris and cilliary epithelium, and deposited on the back corneal surface, lens and zonules, and obstructing the trabecular meshwork, which increases the intraocular pressure.
Using the IR transillumination technique, we can see the iris transillumination defects from this pigment loss. Very dramatic images are often obtained that are not so evident with normal slit lamp exam techniques
Pseudoexfoliation: is a pathologic problem in which deposits of unknown composition and origin appear on lens surfaces, cillary processes, zonules, inner iris surfaces, anterion chamber, and trabecular meshwork. This condition may be associated with high IOP and cataracts.
Iris Nevus / Tumor / Cyst: IR video can be very helpful in differentiating iris nevi vs tumor vs cyst. Iris cysts can look dark on slitlamp exam but usually light up on trans due to the fluid in the cyst. Nevi do not extend beyond what you see and sometimes they are on the posterior iris and not visible from a front slitlamp exam. Often times an iris tumor will have extension into the sclera.
Scleral Tumor: Transillumination the globe allows you to see the extent and borders of an anterior located tumor. Often a surgical procedure can be planned after visualizing the extent of the tumor borders. A big concern is if the tumor is in the cilliary body and would include the iris.
Meibomian Glands: Oil glands withing the eyelid whose duct opens onto the eyelid. Secretions supply the outer portion of the tear film, preventing rapid tear evaporation.
These glands can be visualized using infrared technique to determine if there is meibomian gland dysfunction (MGD).
Adie's Pupil: Pathologic condition characterized by slow pupillary constriction to light, with sluggish redialation and decreased focusing ability for near.
Ocular Albinism: Demonstrated by a lack of pigment in the iris and choroid, and is usually associated with poor vision, light sensitivity (photophobia) and involuntary oscillating eye movements (nystagmus).
Diabetes: Iris abnormalities have been observed in diabetic patients.
Herpes Zoster Iritis: Abnormalities of the iris have been observed in these patients.
Ocular Trama / Surgery / IOFB: Transillumination of the anterior segment and sclera can reveal trama and/or intraocular foreign bodies. Intraocular lens iris rubbing can also be observed.
Research: Infrared technique is used in various research endevors involving humans and animals.