Flare similar after cataract surgery despite sclerocorneal or clear corneal approach

Immediately postop, clear corneal incisions showed less flare, but by 5 months the difference was gone.

MAINZ, Germany — A study designed to investigate the short- and long-term effects of sclerocorneal and clear corneal incisions on postoperative inflammation in cataract surgery found that neither method is associated with severe postoperative inflammation, as measured by laser flare photometry.

Surgical trauma during cataract surgery causes alteration of the blood aqueous barrier (BAB), leading to augmented protein leakage and cellular reaction in the aqueous humor. Although inflammatory complications in uncomplicated cataract surgery are rare, formation of inflammatory sequelae, fibrin reaction and chronic uveitis can occur. To better understand the relationship between postoperative complications and the style of incision used during surgery, H. Burkhard Dick, MD, of Johannes Gutenberg-University in Mainz, Germany, conducted a study to compare the two approaches to cataract surgery.

In this study, Dr. Dick and his team investigated the short- and long-term effect of sclerocorneal and clear corneal incisions on postoperative inflammation. To measure anterior chamber inflammation after surgery, he used a laser flare photometer. A laser flare photometer allows noninvasive, reproducible quantification of aqueous flare intensity by measuring the scatter of a laser beam projected into the anterior chamber.

Recruitment

Patients excluded from the study were those who used topical or systemic steroids, used non-steroidal anti-inflammatory drugs (NSAIDs), were pregnant or attempting to become pregnant, were younger than age 25, had systemic or metabolic diseases, or had pre-existing ocular conditions.

In this prospective, randomized study, 100 patients were enrolled. Sixty-six were female. Patients’ mean age was 72 years, with a range of 30 to 90 years. All patients underwent unilateral surgery.

Patients were divided into two equal-sized groups. In group A, a sclerocorneal incision was used. In group B, a clear corneal incision was performed.

The procedures

In patients undergoing a procedure with a sclerocorneal incision, episcleral tissue dissection at the limbus was performed with scissors. A bipolar wet-field cautery tip was applied to produce blanching of the exposed episcleral vessels. An inverse arched, 300 µm deep scleral groove was made 1.5 mm behind the limbus with a preset diamond step keratome.

The tunnel was prepared parallel to the surface within the sclera using a 3.2 mm diamond keratome. After a 1.5-mm bevel-down corneal course, the anterior chamber was entered and the two-step sclerocorneal tunnel incision was completed.

In those undergoing clear corneal incision, a 300 µm deep groove parallel to the limbus was made at the anterolimbal cornea with a preset, diamond step keratome. Using a clear cornea diamond keratome, a two-step corneal tunnel incision of 2.3 mm to 2.5 mm in length parallel to the iris plane with direction to the endothelium was incised.

Both incision types were located at the temporal site.

Following phacoemulsification, foldable IOLs were inserted with the assistance of one type of viscoelastic. All incisions were left sutureless. At the end of the procedure, all wounds were checked for leakage and found to be watertight. In sclerocorneal incision cases, the conjunctival edges were re-apposed using gentle cautery.

The day after surgery, all patients received prednisolone drops three times per day and at night, as well as gentamicin drops, which were also administered three times per day. Oral steroids or NSAIDs were not administered.

Each patient had a complete eye examination, including slit lamp and retinal examinations and measurement of intraocular pressure, preoperatively, at 6 hours following surgery, at 1 through 3 days, and at 5 months postoperatively.

Following dilatation of the pupil with tropicamide and phenylephrine, aqueous flare was measured with the Kowa laser flare photometer FM-500 by the same examiner on the first, second and third day, and at 5 months postoperatively. In each patient, five replicate measurements were averaged. Aqueous flare per cubic millimeter was calculated for each patient group within each of all five examination periods.

There were no statistically significant differences in flare values between groups at the preoperative stage. Following surgery, absolute individual flare value changes, calculated by subtracting the preoperative flare from the postoperative flare, were significantly lower in the clear corneal incision group at the three daily follow-ups after surgery.

At 5 months, however, differences between groups disappeared. No patient experienced intraoperative or postoperative complications or developed postoperative fibrin formation, Dr. Dick said.

Summing it up

“Both surgical approaches, clear corneal and sclerocorneal incision, were associated with relatively low postoperative inflammation, as measured by laser flare photometry,” Dr. Dick said. “The highest flare values were observed at the 6-hour follow-up and at the first postoperative day, followed by a gradual decline at subsequent follow-ups in both groups. This is in agreement with the results of other studies of BAB alteration after IOL implantation.”

Immediately after surgery, flare was lower in the corneal incision group.

“One explanation for this difference in flare in the clear corneal group compared with the sclerocorneal group may be a slight influx of blood by means of the sclerocorneal incision into the eye that we observed rarely at the end of surgery, leading to higher flare values,” he said. “Indeed, flare was significantly lower after clear corneal incision than sclerocorneal incision at postoperative days 1 through 3, but the extent of BAB alteration was relatively small in both groups.”

Accounting for less flare

Dr. Dick explained that several factors may account for reduced anterior chamber inflammation after phacoemulsification with clear corneal incisions. Decreased risk of iris prolapse, as well as tunnel preparation and surgical manipulation in the avascular cornea, may account for reduced inflammation. Additionally, the clear corneal tunnel incision usually is shorter than the sclerocorneal tunnel incision, resulting in less distortion of the eye during phacoemulsification and irrigation and aspiration.

For Your Information:

H. Burkhard Dick, MD, can be reached at the Department of Ophthalmology, Johannes Gutenberg-University, Langenbeckstr. 1, 55131 Mainz, Germany; +(49) 6131-172533; fax: +(49) 6131-175566; e-mail: bdick@mail.uni-mainz.de. Dr. Dick has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.