Researchers at London's Moorfields Eye Hospital recruited 51 patients from a glaucoma clinic and measured central corneal thickness using an ultrasonic handheld pachymeter by a trained observer three consecutive times over a three-month period. The readings showed clear fluctuation over the period, with a mean difference in CCT of 9.6 ±26.9 µm in the right eye and 19.0 ±29.2 µm in the left. In addition, there was a systematic bias towards increased CCT being recorded at the second reading in both eyes, reaching statistical significance in both the right eye (P=0.02) and the left (P=0.0003). The criteria used to categorize the risk of developing glaucoma in the OHTS were then applied to these results. On the basis of the second reading, 32 percent of eyes required recategorization in both the right and left eyes.
They conclude that CCT measurements taken within a clinical setting by a trained observer may show significant variability. Failure to do more than one CCT reading may result in misclassification and, thus, an inaccurate assignment of risk.
(Ophthalmology 2005; 112:225-228)
Wickham L, Edmunds B, Murdoch I.
Microbial Keratitis Still a Concern With EW Disposable Lenses
The incidence of microbial keratitis with extended wear of low-Dk/t disposable lenses was higher in two prospective post-market clinical trials in India and Australia than that seen in retrospective population-based surveillance studies.
Seven hundred ninety subjects were enrolled at the Prasad Eye Institute, Hyderabad, India from 1993 to 2000, resulting in 1,231 patient eye years; and 167 subjects were enrolled at the Cornea and the Contact Lens Research Unit, Sydney, Australia from1987 to 1999, resulting in 842 patient eye years.
The annualized incidence of microbial keratitis per 10,000 eyes per year of lens wear was 28.9 per 10,000 eyes per year of lens wear (95 percent CI=10.6 to 63) based on combined data from both centers. This equates to 57.0 per 10,000 wearers or 1 in 173 wearers per year of lens wear. All events were rated as slight to moderate in severity and did not result in visual loss.
The investigators advise practitioners and patients to always be alert to signs and symptoms, and practitioners should adopt conservative strategies for diagnosis and management of contact lens-related adverse events.
Holden B, Padmaja S, Sweeney D, Stretton S, Naduvilath T, Rao G.
IOP Rises in a Minority after Silicone Oil Injection
Chronic intraocular pressure elevation occurs in a minority of patients treated with silicone oil, say researchers at the University of Tennessee. Their observational consecutive case series of 450 eyes in 447 patients assessed the incidence and clinical features of chronic elevated IOP after pars plana vitrectomy and silicone oil injection for complicated retinal detachments, and to evaluate the clinical management of eyes with secondary glaucoma. Patients who developed secondary glaucoma were treated medically with antiglaucoma medications and surgically with glaucoma drainage implants placed in an inferior quadrant.
Fifty-one of 450 eyes (11 percent) developed elevated IOP after pars plana vitrectomy and silicone oil injection; 399 eyes (89 percent) did not. Of those that developed elevated IOP, 40 (78 percent) were treated only with glaucoma medicines, which reduced the IOP from a mean ±SD of 26 ±13.4 mmHg before treatment to 18 ±9.1 mmHg after medical treatment (P=0.002). The 11 of 51 eyes (22 percent) with elevated IOP that failed medical therapy were treated surgically with Ahmed Valve implantation within 12 months of silicone oil injection. In the surgical group, IOP was reduced from a mean ±SD of 44 ±11.8 mmHg before surgery to 14 ±4.2 mmHg at the most recent follow-up after surgery (P< 0.001). The number of antiglaucoma medications was reduced from 3.5 ±0.7 before surgery to 1.2 ±0.5 at the most recent follow-up after surgery (P< 0.001). Most of these eyes are effectively treated with antiglaucoma medications. Eyes that do not respond to medical therapy may be effectively managed with glaucoma drainage implant placement in an inferior quadrant.
(J Glaucoma 2005;14:40-46)
Al-Jazzaf A, Netland P, Charles S.
An Unrecognized Cause of the Chronically Irritated Eye
Evaluation of patients presenting with chronically irritated eyes should include distraction of both the upper and lower eyelids and examination for conjunctival inflammation, based on a University of Wisconsin-Madison study. A retrospective, case series reviewed 80 patients (320 eyelids) evaluated from 2000 to 2004 for lax upper and lower eyelids causing chronic irritation. Ten patients with diagnosed floppy eyelid syndrome or obstructive sleep apnea were excluded. Body mass index was calculated for each patient. Lateral tarsal strip fixation of all four eyelids to periosteal flaps based inside the orbital rim was performed to achieve horizontal tightening. Follow-up ranged up to 52 months.
The most common presenting symptoms were epiphora (85.7 percent) and irritation (80 percent). The most common examination findings were upper and lower eyelid horizontal laxity and palpebral conjunctival injection (100 percent patients). Thirteen of 70 patients (18.6 percent) were obese, based on BMI; 26 of 70 patients (37.1 percent) were mildly overweight; 29 of 70 patients (41.4 percent) were normal weight; and 2 of 70 patients (2.9 percent) were underweight. After surgery, 91 percent of patients had improved or resolved symptoms and signs; 2.5 percent of dehiscences occurred with the use of the four-eyelid technique. Gradual continued improvement was observed for up to one year. Acquired lax eyelid syndrome is similar to floppy eyelid syndrome; however, 43.3 percent of patients were normal weight or underweight.
The investigators found the four-eyelid tarsal strip-periosteal flap fixation to be a rapid and effective technique for correction of this syndrome.
(Ophthal Plast Reconstr Surg 2005;21:52-58)
Burka C, Lemke B.