Managing eye disease in primary care. Part 3. When to refer for ophthalmologic care.

Most severe eye diseases and injuries ultimately require intervention by an ophthalmologist. The urgency of referral depends on various factors, including level of vision loss, duration of symptoms, and presence of comorbid diseases. Of special importance are five acute eye problems in which emergency management by primary care physicians can be critical to visual outcome: high-velocity injuries, chemical injuries, acute angle-closure glaucoma, arteritic ischemic optic neuropathy, and central retinal artery occlusion.

Managing eye disease in primary care. Part 2. How to recognize and treat common eye problems.

Many patients with symptomatic eye conditions present initially to their primary care physician. Comprehensive treatment of such conditions as dry eye syndrome, blepharitis, styes, chalazia, conjunctivitis, congenital nasolacrimal duct obstruction, superficial foreign bodies, corneal abrasion, and subconjunctival hemorrhage can often be provided in the primary care setting. Patients with persistent or severe conditions, particularly those involving foreign bodies and corneal abrasions due to high-velocity injuries, should be referred for immediate care by an ophthalmologist.

Managing eye disease in primary care. Part 1. How to screen for occult disease.

Proper eye screening is the first step in detection of occult eye disease in asymptomatic patients. Knowing which patients are at high risk and should be referred for a comprehensive eye examination is the key. In part 1 of this three-part article, Dr Shields explains how to identify high-risk patients and offers practical pointers for performing visual acuity measurements and other necessary testing in children. A list of resources on vision care for both patients and physicians is also included.

Training initiative list scheme (TILS) for minimal access therapy: the MATTUS experience.

The objective of the MATTUS intercollegiate exercise was to set up and audit a training initiative list scheme (TILS) by which funds are awarded to Trust hospitals for operative sessions used specifically for the training of staff in minimal access therapy (MAT). A prospective centralized audit of TILS involving nine Trust hospitals in Scotland over a 12-month period (1 March 1995-end of February 1996) was carried out. These hospitals had contracted for 510 4-h training sessions (389 for minimal access surgery, 121 for allied interventional techniques) by MATTUS accredited consultant tutors. The scheme covered training in technical competence for Minimal Access Surgery (MAS), interventional flexible endoscopy and interventional radiology within Scottish Hospitals. The main outcome measures used in the audit were trainee completion rates, conversion rates, morbidity and mortality, assessment of training received by trainees and assessment of aptitude by the trainers. The results were as follows. Of 510 sessions, 482 (95%) were completed within the deadline. Of these, 463 sessions were audited (367 for MAS, 69 for flexible endoscopy and 27 for interventional radiology). During these sessions, 817 operations/procedures were performed (781 training and 36 developmental). A total of 544 operations were performed during 339 MAS training sessions and 237 radiological/flexible endoscopy procedures in 96 MAT training sessions. The trainee was the principal operator in 643 (82%) procedures and completed the task in 581 (74%) cases. Four per cent of the MAS operations (22/544) required conversion. Post-operative complications occurred in 42 out of 817 patients (5%). Four patients, all with advanced malignancy, died within 30 days of the procedure. Trainees graded 355 sessions as excellent, 109 good, two as average and one as unsatisfactory. The tutors graded their trainees' aptitude to perform the operation as excellent in 34%, good in 53%, average in 11% and poor in < 1%. The training initiative list scheme which allows unhurried training in MAT by consultant tutors using operating sessions that are extra to the service lists is operationally and educationally viable. Furthermore, it can be implemented within a pre-determined budget. The audit of TILS has also demonstrated that the immediate clinical outcome of patients is not compromised by this type of training.

Variability of contact transscleral neodymium:YAG cyclophotocoagulation.

PURPOSE: To study the variability of ciliary body lesions created by contact Nd:YAG cyclophotocoagulation and to evaluate modifications in probe design to reduce this variability. METHODS: Contact transscleral Nd:YAG cyclophotocoagulation was performed on fresh, enucleated porcine eyes in three ways: using a standard, handheld fiber-optic probe (98 eyes); using the same probe with an adjunctive contact lens guide to control for probe pressure, angle, and position (69 eyes); and using a spring-loaded handpiece to control for probe pressure (148 eyes). Four laser lesions were created in each eye and were rated for size and severity of tissue response. RESULTS: For the three groups of eyes, the mean for size differences (largest lesion minus smallest lesion in millimeters for each eye) was 2.53, 1.65, and 2.36, respectively. The mean for severity differences (most severe lesions minus least severe lesion for each eye, based on a four-part subjective rating) was 1.9, 1.1, and 1.7, respectively. These measures of size difference and severity difference were significantly lower with the lens guide than with the other two systems (P = 0.022 and P = 0.020, respectively). CONCLUSIONS: These findings indicate that contact transscleral cyclophotocoagulation can be associated with considerable variation in the size and severity of the ciliary body reaction. This variation has a significant dependence on probe pressure and orientation against the eye and can be reduced by modification in probe design.

Transcorneal erbium laser sclerostomy: towards a guarded laser sclerostomy technique.

PURPOSE: To attempt transcorneal laser sclerostomy with the erbium laser and to control the flow of aqueous through this sclerostomy with a suture ligature. METHODS: A contact erbium laser was used to create sclerostomies through small corneal incisions in both eyes of eight rabbits. Prior to surgery, a Merocel sponge soaked in mitomycin-C (0. 4 mg/cc) was applied to the conjunctiva at the operative site in one eye of each rabbit for 5 min. In the perfused human autopsy eye, following the creation of transcorneal erbium laser sclerostomy, a ligature suture was placed at the limbus around the sclerostomy opening to limit fluid flow. RESULTS: Using the erbium laser probe and the transcorneal approach, patent sclerostomies were created in all eyes. Intraocular pressures were significantly lower in mitomycin-C-treated eyes up to four months postoperatively (p = 0. 05). Eyes not treated with mitomycin-C demonstrated failure of filtering blebs by 1 month postoperatively (mean bleb survival = 9. 3 days). All mitomycin-C-treated eyes showed evidence of bleb formation up to 4 months postoperatively. Histologic examination of transcorneal sclerostomies in rabbit eyes showed patent sclerostomies at 1 day postoperatively with minimal adjacent thermal damage. In perfused human autopsy eyes, intraocular pressure was maintained near preoperative levels following placement of a ligature suture around the sclerostomy and decreased with release of the suture. CONCLUSIONS: These results demonstrate that functional filtering blebs can be created via small transcorneal incisions using the erbium laser. Transconjunctival mitomycin-C produces lower postoperative intraocular pressures and prolongs bleb survival. Aqueous flow through the sclerostomy was controlled with a suture ligature.

Enhancement of filtration surgery with cytosine arabinoside and reversal of toxicity with 2'-deoxycytidine.

Antifibrosis agents have improved the success of glaucoma filtration surgery, although undesired side effects are not readily reversible and may present a major limitation in the use of these agents. Our purpose was to study the efficacy of cytosine arabinoside (Ara-C) as an adjunctive antimetabolite in glaucoma surgery in the rabbit, and reversal of toxicity due to this agent with the competitive inhibitor 2'-deoxycytidine. Posterior lip sclerectomy was performed in rabbit eyes treated with 15 mg subconjunctival Ara-C daily for 7 d then every other day for 7 d. Mean intraocular pressure was lower in eyes treated with Ara-C compared with controls at all time points following filtration surgery. On the 10th postoperative day, the mean intraocular pressure of control eyes (25.0 +/- 1.9 mm Hg) had returned to baseline levels, whereas the intraocular pressure of eyes treated with Ara-C was significantly lower (16.0 +/- 1.7 mm Hg) (P < 0.001). Bleb survival was also prolonged in the Ara-C-treated eyes. The major ocular side effect of Ara-C was corneal toxicity, with epithelial defects in 40% of eyes after 8 daily injections of 15 mg Ara-C. Reversal of toxicity was enhanced with 2'-deoxycytidine, with complete resolution of epithelial toxicity after 6.5 +/- 1.7 d following daily topical 10% 2'-deoxycytidine compared with 12.7 +/- 0.58 for control (P < 0.002). These results demonstrate that postoperative subconjunctival injection of Ara-C results in improved bleb function after filtration surgery in the rabbit. Recovery from corneal epithelial toxicity due to Ara-C is markedly enhanced with the competitive inhibitor 2'-deoxycytidine.

Videographic and histologic comparison of Nd:YAG and diode laser contact transscleral cyclophotocoagulation.

We performed contact transscleral cyclophotocoagulation in two human autopsy eyes with continuous-wave Nd:YAG and diode lasers. Duration of exposure was two seconds, and powers were 4 to 7.3 W with the Nd:YAG laser and 1.75 to 2.5 W with the diode laser. In both procedures, we used hand-held quartz fiberoptic contact probes for energy delivery. Tissue responses were viewed with high-magnification videographic recording technique to analyze the real-time laser effects. The treated tissues were then studied by light microscopy. We observed different tissue responses both videographically and histologically. Nd:YAG laser lesions were characterized by prominent tissue whitening and contraction of the ciliary epithelium, while the diode laser lesions had less whitening and the tissue contraction appeared to be deeper in the ciliary body. The histologic correlate was coagulation and disruption of the ciliary epithelium and little effect on the underlying ciliary muscle with the Nd:YAG laser, while the diode laser had less effect on the ciliary epithelium but caused a significant coagulative response in the ciliary muscle. Comparative trials are needed to establish the clinical significance of these videographic and histologic observations.

The influence of exposure duration in transscleral Nd:YAG laser cyclophotocoagulation.

Transscleral cyclophotocoagulation was performed in human autopsy eyes by using three Nd:YAG lasers with different durations of exposure: a pulsed, contact laser with a duration of 0.75 millisecond and a range of one to ten pulses per burst (GLase 106, Sunrise Technologies, Fremont, California); a pulsed, noncontact laser with a duration of 20 milliseconds (Microruptor 2, Lasag Medical Lasers, Thun, Switzerland); and a continuous-wave, contact laser with durations of 700 and 2,000 milliseconds (Microruptor 3, Lasag Medical Lasers, Thun, Switzerland). Tissue responses were observed with a high-magnification videographic recording technique to analyze the immediate, real-time laser effects, and by light microscopy to characterize the laser-induced lesions further. Videographically, both pulsed lasers were noted to cause mild whitening of the pigment epithelium with frequent vaporization and explosive tissue disintegration. Histologically, the 0.75-millisecond pulse typically produced the most marked epithelial disruption, referred to as an explosive-like lesion, whereas the 20-millisecond pulse more often caused moderate tissue disruption with elevation of the epithelial layers in a blister-like lesion. In contrast, the continuous-wave laser was observed videographically to produce prominent tissue whitening and puckering, seen histologically as convolution of the epithelium and coagulation of stroma, which was called a shrinkage-like lesion. Our study suggests that exposure duration influences in vitro tissue response to transscleral Nd:YAG cyclophotocoagulation, although in vivo studies and clinical trials are needed to determine which tissue response is optimum for clinical use.

In vitro videographic comparison of argon and Nd:YAG laser iridotomy.

We used an in vitro technique with high-magnification video recording to evaluate from the posterior side of the iris the immediate sequence of events during argon and Nd:YAG laser peripheral iridotomy. The observed effects differed strikingly. The argon laser caused a gradual mounding up of iris pigment epithelium with each successive energy application before final penetration. This effect was reduced but not eliminated with higher power levels. The Nd:YAG laser caused complete disruption and dispersal of the pigment epithelium with a single pulse of energy. Additionally, a multiple focal point configuration of the Nd:YAG laser was observed to produce a significantly larger iridotomy than a single focal point configuration for comparable energy settings. These observations may in part explain the observed clinical advantage of the Nd:YAG laser over the argon laser for creation of a patent iridotomy.