Timing of initial screening examinations for retinopathy of prematurity.

OBJECTIVE: To test a screening protocol for retinopathy of prematurity (ROP) that uses the dual criteria of postconceptional age and chronological age, rather than a single parameter, to determine precisely when to begin eye examinations. METHODS: We retrospectively reviewed medical records of 179 infants (326 eyes) who had undergone laser treatment for threshold ROP. We entered their chronological and postconceptional ages at treatment into a database and evaluated various screening parameters to determine the combination of criteria that would allow us to safely postpone the initial eye examinations. RESULTS: Screening infants at 7 weeks of chronological age or 34 weeks of postconceptional age (whichever comes first), but not before 5 weeks of chronological age, seems to reliably detect the onset of threshold ROP while reducing the number of unnecessary early examinations. CONCLUSION: Simultaneously applied dual criteria of chronological age and postconceptional age may be a superior method of determining when to initiate ROP examinations and is preferable to using either chronological age or postconceptional age alone.

Acquired cataracts after argon laser photocoagulation for retinopathy of prematurity.

PURPOSE: Our purpose was to determine the incidence of cataract after argon laser photocoagulation of the retina in infants with retinopathy of prematurity (ROP). METHODS: We reviewed medical records of 189 consecutive infants undergoing argon laser photocoagulation for acute ROP between 1993 and 1996. Birth weight, estimated gestational age at birth, chronologic and postconceptional ages at the time of treatment, ROP outcome, and the postoperative occurrence of cataract were recorded. RESULTS: A total of 374 eyes in 189 infants were treated for threshold ROP. Mean birth weight was 916 gm (range 480 to 2500 gm), mean postconception age at birth was 26.4 weeks (range 23.5 to 34 weeks), and mean postconception age at surgery was 36.2 weeks (range 33 to 47 weeks). A favorable anatomic outcome occurred in 90% of eyes. However, severe macular traction, macular fold, or retinal detachment developed in 10% of eyes. A total of four eyes (1%) had cataracts. Laser-induced cataracts were diagnosed in only two eyes. A third eye had a posterior subcapsular cataract that may or may not have resulted from the laser treatment. In a fourth patient a unilateral punctate opacity judged to be visually insignificant was noted at surgery but it was not progressive. All patients who had cataracts had a persistent tunica vasculosa lentis; however, there was no statistically significant difference in the incidence of cataract formation in eyes with persistent tunica vasculosa lentis compared with eyes without it (p = 0.057). CONCLUSION: Argon laser photocoagulation remains an effective alternative to transscleral cryotherapy in the treatment of threshold ROP. The incidence of cataract formation is approximately 1% and may be more likely to occur when persistent hyaloidal vessels are present on the lens.

The predictive value of posterior pole vessels in retinopathy of prematurity.

Dilation and tortuosity of the posterior pole vessels "(plus disease)" is a sign of poor prognosis and may be associated with threshold or prethreshold retinopathy of prematurity (ROP). We have found that normal posterior pole vessels are a reliable marker for the absence of stage 3 ROP. One hundred thirty-two consecutive premature infants weighing less than 1600 g at birth underwent ROP examinations between 32 and 40 weeks' postconceptional age. The status of the posterior pole vessels was compared to peripheral retinal pathology. Vascular findings in the posterior pole were graded 0, 1, 2, or 3, with 0 representing normal arterioles and venules and 3 representing plus disease. The remainder of the fundus examination was recorded using the international Classification of ROP, then converted to a severity scale based on zone and stage of ROP. For each infant, only one examination representing the most severe stage of ROP reached prior to treatment or spontaneous regression was used for data analysis. There was a highly significant Spearman's rank correlation (rs = 0.65) between the posterior pole vascular abnormalities and the severity of ROP in the retinal periphery. Clinically important ROP was not found in any patient with normal posterior pole vessels (grade 0) and stage 3 disease was usually associated with both venous and arterial vascular abnormalities (grades 2 or 3). When ocular examination of premature infants is difficult because of poor dilation of the pupil, hazy media, or medical instability, normal appearance of the posterior pole vessels can be a reassuring finding if it is necessary to postpone complete fundus examination in infants at risk for ROP.

Tying the knot. Is it always necessary?

Securing the final muscle position during adjustable-suture strabismus surgery is usually accomplished by tying the sutures in a knot in the early postoperative period. Even patients who have satisfactory ocular alignment without adjustment require manipulation of inflamed ocular tissues to secure the muscle. In our experience, approximately half of these cases are not adjusted. We have devised a technique in which postoperative knot tying is required only in those patients who actually undergo adjustment. In our series of 42 patients who underwent adjustable-suture surgery, 22 cases were not adjusted and 30 cases were left untied. No instances of muscle slippage occurred. We believe this reduction in postoperative manipulation represents an improvement in adjustable-suture strabismus surgery.