American patients with primary open-angle glaucoma enrolled in commercial managed care plans are receiving care consistent with the American Academy of Ophthalmology's Preferred Practice Pattern, in most cases, reports a U.S. study team. They reviewed the records of nearly 400 working-age patients with POAG enrolled in six managed-care plans between 1997 and 1999.

Practice patterns for many processes of care were consistent with AAO's PPP. In 88 to 99 percent of initial evaluations, both ophthalmologists and optometrists performed visual acuity, intraocular pressure, and slit-lamp examinations, optic disc and nerve fiber layer evaluations, and fundus evaluations. Most patients also received a pupil examination (74 percent).

Other key patterns of care were not consistent with the PPP. Only 66 percent took a visual field test; less than half had a gonioscopy during the initial exam. Just over half (53 percent) of patients did not have a photograph or drawing of the optic nerve head, a finding the investigators consider "worrisome" since it represents a lack of a baseline image. Documenting a target IOP in writing was done by only 1.3 percent of doctors at initial evaluation. While most follow-up visits were conducted during the recommended time period, researchers were nonetheless surprised at the number of patients with moderate-to-severe damage who went more than 12 months and more than 24 months without another exam (See Table 1).

Table 1. Visual Field Test Intervals by Severity of Glaucomatous Damage
Severity
Interval between Visual Field Tests (mo.)	Mild	Moderate-to-Severe	P Value
</= 3	2.9	4.0
3-6	4.7	13.1
6-12	30.5	39.5	<.001
12-24	48.2	34.9
>24	13.7	8.6

Because all information from this study was gleaned from records (i.e., lacking, for example, patient compliance information), the re-searchers suggest that their study be viewed as describing care actually received by patients with POAG, and not necessarily that recommended by the providers.
(Arch Ophthalmol 2003;121:777-783)
Fremont A, Lee P, Mangione C, Kapur K, Adams J,
Wickstrom S, Escarce J

Heavy Silicone Oil Works as Tamponade
German researchers report good intraocular tolerance of heavy silicone oil as a tamponade in complicated retinal detachment. They found that the specific gravity of a silicone oil-RMN3 mixture (Oxane HD, Bausch & Lomb) (See Table 2) allows for sufficient tamponade of inferior retinal tears for at least three months without significant side effects.

For this prospective study, researchers recruited patients with a complicated retinal detachment involving the inferior part of the retina requiring internal tamponade with silicone oil. Inclusion criteria were retinal detachment secondary to proliferative vitreoretinopathy, inferior or posterior tears, or penetrating trauma, resulting in 35 eyes of 35 patients.

Table 2. Chemical and Physical Properties of Heavy Silicone Oil
Density	1.03 g/cm3
Viscosity	3,800 cSt
Surface Tension	>40 mN/m
Refractive Index	1.40
Volatility	<0.1%
RMN3* volume	11.9%
*RMN3,  mixed fluorinated and hydrocarbonated olefin

Retinal reattachment at the posterior pole and in the inferior quadrants was achieved in 91 percent of cases at the one-month follow-up visit. They observed residual retinal detachments in the su-perior quadrants in six eyes. Complications included in-creased IOP in six eyes, in-traocular inflammation and synechia formation in one eye, a central retinal artery occlusion after heavy oil re-moval in one eye, and scattered retinal hemorrhages in two eyes. They did not ob-serve significant emulsification during tamponade. At the last follow-up, all eyes had macular at-tachment, and 24 eyes had a visual acuity better than or equal to 20/400.
(Retina 2003;23:335-342)
Wolf S, Schön V, Meier P, Wiedemann P

24-Hour Monitoring Wise in Glaucoma Management
A research team in the United Kingdom supports the value of 24-hour IOP monitoring in routine clinical practice, following their retrospective study of 29 glaucoma patients. These patients had been selected for inpatient monitoring because of progressive glaucoma in spite of what seemed to be good IOP control.

Researchers found that 24-hour monitoring of IOP and the consequent identification of IOP fluctuations and spikes led to a change in clinical glaucoma management in 79 percent of patients. Of these cases, eight had alterations to their topical treatment, two received argon laser trabeculoplasty, and 13 underwent or were offered trabeculectomy.

While there was no statistically significant difference between the mean clinic IOP measurements and those taken over the 24-hour period, the peak IOP during the monitoring was 4.9 mmHg higher on average than the peak clinic IOP (P=0.0001). The timing of the IOP peak during the 24-hour monitoring followed no apparent pattern, with 11 patients peaking in the morning (6-11:30 a.m.), eight peaking in the afternoon (12-5:30 p.m.) and 10 peaking in the evening (6 p.m. to 12 a.m.). Overall, 15 patients had their peak IOP measurements outside of normal U.K. office hours (9 a.m. to 5 p.m.).
(Journal of Glaucoma 2003;12:232-236)
Hughes E, Spry P, Diamond J

Microkeratome Design, Patient Age Linked to Corneal Abrasion
In a retrospective chart review of 263 eyes, researchers at Johns Hopkins determined that the incidence of intraoperative corneal abrasions is significantly higher with the Hansatome microkeratome (Bausch & Lomb Surgical) than with the Amadeus microkeratome (Advanced Medical Optics) (P = .014).
They also found a significant correlation between increasing patient age and the incidence of corneal abrasions with both microkeratomes (P < .05).

Patients undergoing elective LASIK were randomized for surgery by one of two surgeons and to one of two microkeratomes—the Hansatome (oscillation rate 11,400 osc/min, drive 1.4 mm/sec) and the Amadeus (16,000 osc/min, 
3.0 mm/sec). There was no difference in the pharmaceutical preparation of the pa-tients preoperatively, the intraoperative instruments for LASIK or the surgical technique.

One hundred fifty eyes had LASIK with the Hansatome. Of these, nine suffered corneal abrasions that did not require a bandage contact lens and 10 had abrasions that did require a BCL. One hundred thirteen eyes underwent LASIK with the Amadeus, and of these, one suffered a corneal abrasion that did not require a bandage contact lens and three had abrasions that did require a BCL.

In those patients undergoing LASIK with the Hansatome, the mean age for those with abrasions was 48.2±9.3; for those without abrasions, the mean age was 43.4±10.7. With the Amadeus, the mean age of patients who suffered abrasions was 51.2±9.3; for those without abrasions, it was 42.3±11.0. Researchers believe that age-related changes in the epithelial basement membrane zone may partly explain the increased occurrence of epithelial injury correlated with increasing age of patients in this study.

Researchers add that although  more women were present in the corneal abrasion group than in the normal group (16 vs. 7 ), the difference was not statistically significant. They recommend discussing the higher risk of corneal abrasions with LASIK candidates of older age. 
(J Cataract Refract Surg 2003; 29:1174-1178)
Jabbur N, O'Brien T