March 2010

 

OPHTHALMOLOGY NEWS

 

Changes in anterior depth


by Matt Young EyeWorld Contributing Editor

   
Contusions can impact anterior chamber depth but long-term clinical signifcance has yet to be determined Source: Manolette Roque, M.D.

New research finds that contusion can lead to changes in anterior chamber depth, but the exact clinical significance of this has yet to be determined. Researchers, lead by Kenji Kashiwagi, M.D., Department of Ophthalmology, Faculty of Medicine, University of Yamanashi, Tamaho, Japan, found that contused eyes had greater ACD figures in both peripheral and central areas. “The difference in ACD between the contused and noncontused eyes tended to increase with greater distance from the center,” Dr. Kashiwagi reported. The study was published online in August 2009 in Ophthalmic Research. “Even mild contusion could influence ACD particularly in the peripheral region.”

Measuring ACD

Dr. Kashiwagi analyzed eyes in patients whose chief complaint was unilateral contusion that had occurred within six days of their physician visit. These patients had no evidence of angle recession by gonioscopy, and they had no history of ocular diseases or ocular surgery before trauma. They were analyzed using a scanning peripheral anterior chamber depth analyzer. “SPAC is an optical analyzer that measures ACD from the central to the peripheral region, producing a total of 21 consecutive ACD images,” Dr. Kashiwagi noted. “The images are subjected to image processing analysis.”

Thirty-seven patients satisfied the criteria. Fourteen had commotion retinae, and 15 had no ocular issues related to contusion. “The mean SPAC-determined ACD grades of contused and noncontused eyes were 10.7 +/–1.6 and 9.8 +/–2.1, respectively, demonstrating that the contused eyes had significantly larger ACD values than the noncontused ones,” Dr. Kashiwagi reported. Nonetheless, there was no serious impact of either the contusions or the increased anterior chamber depth. “Twelve participants complained of visual acuity loss on their first visit, but all of them recovered their visual acuity during the 1-month period after the trauma,” Dr. Kashiwagi noted. “There were no significant differences in best-corrected visual acuity and intraocular pressure between the contused and the noncontused eyes.”

That said, contusion can contribute to ocular problems. “The anterior chamber depth (ACD) is intricately involved in aqueous humor circulation, intraocular pressure (IOP) and refraction,” Dr. Kashiwagi reported. “Contusion sometimes contributes to changes in the ACD, causing damage of the angle, change in refraction, IOP elevation/reduction and cataract.”

Certainly, contused eyes had distinct differences from noncontused eyes. “The contused eyes had larger ACD values than the noncontused ones at all measured points in the peripheral region,” Dr. Kashiwagi reported. “Our findings show that ACD could be affected even by a minor contusion that does not result in severe hyphema or visual acuity loss.”

Dr. Kashiwagi followed up on six contusion patients for 10 months, in some cases, and found that ACD values did decrease over time. “We may have to pay better attention to the change in ACD particularly in the peripheral region when we examine contused eyes,” Dr. Kashiwagi noted. This study yields insights into the SPAC as a device that may be helpful in measuring ACD but also has its limitations. “SPAC can evaluate ACD only on the lateral side and cannot evaluate ACD of eyes showing severe hyphema, corneal distortion or opacity, or severe loss of visual acuity,” Dr. Kashiwagi reported. “Since we did not have quantitative ACD data of the enrolled patients before contusion, we cannot completely disregard the possibility that the contused eyes may have had much larger ACD values prior to the unilateral contusion.”

The SPAC nonetheless helps to reveal previously unchartered terrain. “Although it is difficult to evaluate slight changes in ACD particularly in the peripheral region, SPAC has enabled us to evaluate peripheral ACD quantitatively,” Dr. Kashiwagi reported. Abhay R. Vasavada, M.D., director, Iladevi Cataract & IOL Research Centre, Raghudeep Eye Clinic, Ahmedabad, India, suggested a deepened anterior chamber “could be a sinister sign.” When there is an impact on the globe, Dr. Vasavada said there is an impact on structures such as the zonules. “The zonules, which support the lens, are pushed back,” Dr. Vasavada said. “Eventually, many of these trauma patients develop a cataract, and when you need to remove it, the [weakened] zonules will add to the possibility of a dropped nucleus.”

Such cataract surgery would require much more surgical planning. “A deep chamber is not a good thing,” Dr. Vasavada said. He added that trauma could cause movement to be transmitted to the vitreous body and the macula, and a deepened anterior chamber could be a sign that that has happened. Nonetheless, a simple hyphema likely wouldn’t be enough to cause severe ocular damage. “That can give rise to higher IOP temporarily, but otherwise, the patient should be fine,” Dr. Vasavada said.

Editors’ note: Dr. Kashiwagi has a patent for one of the instruments used in this study. Dr. Vasavada has no financial interests related to his comments.

Contact information

Kashiwagi: +81 552 73 9657, kenjik@yamanashi.ac.jp
Vasavada: +91 7927490909, icirc@abhayvasavada.com

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