November 2008

 

CATARACT/ IOL

 

When seeing is better than believing


by Matt Young EyeWorld Contributing Editor

   
This patient has anterior basement membrane dystrophy (ABMD) changes in the epithelium, which is viewed here with a slit lamp. The slit lamp still is a very useful tool even in an age of new advances in imaging technology Source: Christopher Rapuano, M.D.

Ophthalmologists know posterior capsule rupture can occur after nonpenetrating ocular injury. Their knowledge of this problem could be further enhanced by Scheimpflug imaging, which was used recently in just such a case for possibly the first time to visualize and quantify the posterior capsule rupture size. “When TPCR [traumatic posterior capsule rupture] occurs, the extent of rupture, amount of residual nucleus and cortex, and presence or absence of vitreous prolapse in the anterior chamber are all variable factors which can be documented with Scheimpflug imaging,” according to Dilraj Grewal, M.D., Bascom Palmer Eye Institute, Palm Beach Gardens, Fla. Dr. Grewal reported these findings in the May-June 2008 issue of the European Journal of Ophthalmology.

An in-depth look

Dr. Grewal analyzed an 11-year-old boy two days after blunt trauma occurred to the left eye. It was caused by a slingshot. BCVA was 20/20 in the right eye and 20/400 in the affected left eye. “Slit lamp biomicroscopy revealed a Vossius ring traumatic cataract, traumatic posterior capsular rupture (TPCR) with bulging out of lens cortex,” Dr. Grewal reported. “Gonioscopy revealed a 360-degree angle recession. It was a closed globe injury, Type B, Grade 3, Zone 3 RAPD negative.” Further, Scheimpflug imaging (Pentacam 70700, Oculus, Wetzlar, Germany) was used. According to the manufacturers: “The Pentacam is a rotating Scheimpflug camera which captures Scheimpflug images of the anterior eye segment. The Scheimpflug technique provides sharp and crisp images that include information from the anterior corneal surface to the posterior crystalline [capsule].

The key advantages of the rotating imaging process are the precise measurement of the central cornea, the correction of eye movements, the easy fixation for the patients and the extremely short examination time.” The Pentacam could be used by corneal refractive surgeons and cataract surgeons. It could be used in examinations from general screenings to glaucoma screenings, providing the following: anterior and posterior corneal topography and elevation maps, corneal pachymetry, 3D-chamber analyzing, lens density, tomography, and improved IOL-calculation. In this case, it was used to further analyze posterior capsule rupture. “Traumatic cataract in region of TPCR was evidenced by increased lens density at cortex-vitreous interface,” Dr. Grewal noted. Scheimpflug imaging showed posterior pseudo-lenticonus, or lens material bulging through the posterior capsule rupture. It was able to measure the size of the posterior capsule opening, which was 5920 microns x 3880 microns preoperatively.

After surgery, it was able to visualize a well-centered IOL, “increased density along the short axis of TPCR,” and “increased density along the long axis of TPCR,” Dr. Grewal reported. The posterior capsule opening postoperatively measured 4840 microns x 3970 microns, as determined by Scheimpflug imaging. After phacoemulsification with and IOL implant was carried out, BCVA reached 20/20 in the affected eye. “I think that’s really a great use of technology,” said Mark Packer, M.D., clinical associate professor of ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Ore., in reference to Scheimpflug imaging for analyzing a posterior capsule rupture. Nonetheless, he doesn’t consider it to be an essential technology moving forward to help diagnose and treat posterior capsule rupture. “This could be done at the slit lamp,” he said. “You could just use a slit lamp and make the same diagnosis. It’s just an optical measurement technique.” He added, “ I have thought about [Scheimpflug imaging] as a very expensive slit lamp.” Nonetheless, Dr. Packer said, Scheimpflug imaging does add an element of precision. “You could grade cataracts this way and correlate them with effective phaco time,” he said. He wondered, however, about the patient’s age in this case, suggesting that very young children could have trouble sitting still for image taking. There are other technologies in play that also are elucidating ocular problems like never before. Ultrasound, for instance, could help analyze a posterior cataract, he said. Nonetheless, the use of Scheimpflug imaging to examine posterior capsule rupture demonstrates the versatility of this technology, and “how inventive surgeons can be,” Dr. Packer said.

Clearly, in this case study, Scheimpflug imaging was used in addition to slit lamp biomicroscopy and gonioscopy rather than in place of these devices. For the moment, Scheimpflug imaging—at least for analyzing posterior capsule rupture—appears to be an additional help, rather than a replacement technology.

Editors’ note: Dr. Grewal has no financial interests related to this study. Dr. Packer has no financial interests related to his comments.

Contact information:

Grewal: Dilraj@gmail.com

Packer: 541-687-2110 , mpacker@finemd.com

       
When seeing is better than believing When seeing is better than believing
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