Effects of sickle cell anemia on conjunctival oxygen tension and temperature.

Because conjunctival vessels are affected by sickle cell disease, we wanted to see if conjunctival PO2 (partial oxygen tension) and temperature were also affected and if these measurements could aid in managing these patients. Conjunctival PO2 and temperature in 23 asymptomatic homozygous patients with sickle cell anemia did not differ significantly from those in age-matched controls. However, 12 subjects in painful sickle cell crisis had a significantly lower conjunctival PO2 than before crisis despite no significant change in hematocrit and conjunctival temperature. Supplemental oxygen therapy significantly increased conjunctival PO2. When supplemental oxygen was removed, conjunctival PO2 decreased to the admission level despite clinical improvement. This finding supports the use of supplemental oxygen in treating crisis. Measuring conjunctival PO2 can give clinicians an assessment of the effect of sickle cell disease on a peripheral capillary bed and may provide the first objective method to reliably diagnose acute painful sickle cell crisis.

Tocopherol efficacy and safety for preventing retinopathy of prematurity: a randomized, controlled, double-masked trial.

To test the efficacy and safety of vitamin E in preventing retinopathy of prematurity, 287 infants with birth weights of less than 1.5 kg or gestational ages of less than 33 weeks were enrolled within 24 hours of birth in a randomized, double-masked trial of IV, followed by oral, placebo v tocopherol (adjusted to plasma levels of 3 to 3.5 mg/dL). In the 196 infants completing ophthalmic follow-up, tocopherol did not prevent retinopathy of prematurity of any stage (28% placebo treated v 26% tocopherol treated) or moderately severe retinopathy of prematurity (8% placebo treated v 11% tocopherol treated). Cicatricial sequelae were not significantly different (1/97 placebo treated v 3/99 tocopherol treated), with one placebo-treated infant and one tocopherol-treated infant having retinal detachments. Among all 232 infants examined, those treated with tocopherol had more retinal hemorrhage than placebo-treated infants (8/121 placebo treated v 16/111 tocopherol treated), and retinal hemorrhage correlated positively (P less than .01) with plasma levels of tocopherol after the first 2 weeks of age. Prospective monitoring of morbidity including late-onset sepsis, necrotizing enterocolitis, etc revealed no differences between groups except that grades 3 and 4 intraventricular hemorrhage occurred more frequently in infants weighing less than 1 kg at birth who had received tocopherol (14/42, 33%) v those who had received placebo (4/43, 9%) (P less than .02). Our data do not support the use of tocopherol for prophylaxis against retinopathy of prematurity in premature infants and suggest that IV tocopherol treatment starting on day 1 may increase the incidence of hemorrhagic complications of prematurity, particularly in infants with birth weights of less than 1 kg.

Conjunctival hypoxia in diabetes mellitus.

A frequently cited theory for the pathogenesis of neovascularization in diabetic retinopathy is that retinal hypoxia and/or ischemia release a factor which stimulates neovascularization. To the authors' knowledge, there is no direct in vivo evidence in the human proving this theory. One hundred and twenty-two diabetic subjects were studied to see whether worsening retinopathy was associated with changes in conjunctival oxygen tension (pO2). Diabetics without retinopathy had a conjunctival pO2 which was similar to an age-matched normal population. Diabetics with only background retinopathy had a significantly lower conjunctival pO2 than those without retinopathy (P less than 0.01). Diabetics with proliferative retinopathy showed a conjunctival pO2 that was significantly lower than either of the first two groups (P less than 0.05). The lowest value of all was found in patients with rubeosis iridis. Duration of diabetes alone did not correlate significantly to conjunctival pO2. These findings support the hypoxic theory of diabetic neovascular retinopathy.

Effect of phenylephrine hydrochloride on conjunctival PO2.

Phenylephrine hydrochloride eyedrops induce vasoconstriction through alpha-adrenergic mechanisms. Ten subjects underwent a 46% reduction in conjunctival PO2 when 2.5% phenylephrine eyedrops were administered. Compared with a control group, this reduction was significant. The induced conjunctival hypoxia lasted about 80 minutes. These findings suggest a number of clinical implications.

Chemical preparation of the eye in ophthalmic surgery. IV. Comparison of povidone-iodine on the conjunctiva with a prophylactic antibiotic.

We previously found that half-strength (5%) povidone-iodine solution significantly reduced the bacterial flora of the conjunctiva. To compare the antibacterial effect of a topical combination antibiotic (Neosporin ophthalmic solution) given three times daily for three days preoperatively with that of half-strength povidone-iodine solution given as part of the preoperative preparation, conjunctival cultures were studied from 35 patients undergoing ocular surgery. When used individually, the antibiotic and povidone-iodine solutions caused a similar and substantial decrease in the number of colonies and species of bacteria cultured. When both drugs were used together, the decrease was even more striking, making 83% of the conjunctivae sterile. To minimize bacterial flora before ocular surgery, we recommend that a broad-spectrum topical antibiotic be given for three days preoperatively and that half-strength povidone-iodine solution be used as part of the preoperative preparation.

Familial, congenital paralysis of horizontal gaze.

Eye movements were studied in a sister and brother with familial, congenital paralysis of horizontal gaze. Horizontal and vertical eye movements were recorded with DC electro-oculography and analyzed with a laboratory computer. All horizontal, conjugate eye movements were absent (saccades, pursuit, optokinetic nystagmus, vestibulo-ocular response, and visual-vestibular responses). Voluntary vergence eye movements were preserved and were used to track visual targets. An involuntary, horizontal, pendular nystagmus was found to represent disconjugate, smooth, vergence eye movements. Vertical saccades and vestibulo-ocular responses were normal. However, vertical pursuit, optokinetic nystagmus, and suppression of the vestibulo-ocular response by fixation were impaired. A developmental anomaly affecting motor neurons and interneurons in the abducens nuclei is suggested to be the cause of the absence of conjugate, horizontal eye movements.

Development of tearing in preterm and term neonates.

BACKGROUND: Although term and preterm infants have the capacity to secrete tears, the relative contribution of basal and reflex secretion of tears has not been previously assessed together in a prospective study. This information potentially has practical clinical importance. OBJECTIVES: To measure basal and reflex tear secretion in preterm (30-37 weeks after conception) and term (38-42 weeks) newborns and to determine the developmental pattern of tear production. METHODS: Tear secretion was evaluated by applying Schirmer tear test strips to the inferior fornix for 5 minutes before (reflex plus basal secretion) and after (basal secretion) applying a topical anesthetic agent. RESULTS: Seventy infants (36 preterm and 34 term) were tested. Mean (+/- SD) basal tear secretion was 6.2 (+/- 4.5) mm in preterm and 9.2 (+/- 4.3) mm in term infants and increased progressively with increasing weight (P<.001) for all newborns. Mean (+/- SD) reflex tear secretion was 7.4 (+/- 4.8) mm in preterm and 13.2 (+/- 6.5) mm in term infants and also increased with increasing weight (P<.001) for all newborns. CONCLUSIONS: Preterm infants have reduced reflex and basal tear secretion. This may mask the diagnosis of a nasolacrimal duct obstruction, concentrate topically applied medications, and allow corneas to quickly become dry during ophthalmological examination and treatment. By term, tear production in newborns is similar to that in adults.

The effectiveness of daily wear contact lenses for the correction of infantile aphakia.

OBJECTIVE: To evaluate the effectiveness and safety of daily wear contact lenses in the treatment of infantile aphakia. DESIGN: A study of prognosis using a cohort followed up for a mean of 58 months. SETTING: All operations, contact lens care, and follow-up were conducted at a university referral center. PATIENTS: Of 111 children undergoing surgery for cataract between 1980 and 1990, 51 (68 eyes) met the criteria of age younger than 2 years at the time of surgery and of cataract of nontraumatic origin. Patients were evaluated for visual acuity, complications, number of contact lenses worn per year, and changes in contact lens refractive power per month. A subgroup of 28 eyes of patients undergoing surgery before age 7 months and followed up for at least 24 months was studied. INTERVENTION: Following cataract surgery, all patients were fitted with daily wear contact lenses. MAIN OUTCOME MEASURE: Final visual acuity and complications were studied. The distribution of mean contact lens power for each month of age was determined. RESULTS: During the follow-up period, no serious complications were encountered. The visual acuity outcome was better following bilateral cataract surgery than unilateral surgery (P < .001 using chi 2 analysis) and was comparable with that achieved with extended wear contact lenses. CONCLUSION: Daily wear contact lenses were found to be safe and effective in the treatment of infantile surgical aphakia. The daily care was easily learned by the parents.

Ocular involvement in patients with posttransplant lymphoproliferative disorder.

OBJECTIVES: To describe ocular disease in 3 patients with posttransplant lymphoproliferative disorder (PTLD) and to identify the frequency of such ocular involvement. METHODS: Medical record reviews. Using Kaplan-Meier analysis, we calculated the frequency of ocular involvement among pediatric patients with systemic PTLD after liver transplantation. RESULTS: Each patient had bilateral anterior chamber cells. Biopsy of an iris nodule from a patient who had undergone cardiac transplantation confirmed the diagnosis of PTLD, but no signs of systemic PTLD were found. The other 2 patients had systemic PTLD after liver transplantation; 1 presented with iris nodules in both eyes and a subretinal mass in the left eye, while the other had bilateral anterior chamber cells only. Ocular signs improved slowly after reduction of immunosuppressive drug therapy. Ophthalmological examinations were performed on 22 of 25 pediatric patients with PTLD after liver transplantation; 2 had ocular disease. Kaplan-Meier analysis indicated a 20% risk of ocular involvement at 3 years after development of PTLD (95% confidence intervals, 0%-50%). CONCLUSIONS: Posttransplant lymphoproliferative disorder should be considered in the differential diagnosis of uveitis after organ transplantation. Anterior chamber cells and iris nodules are the most common ocular signs, but the posterior segment can be involved. Ocular involvement can occur without evidence of systemic disease and can be asymptomatic. Reduction of immunosuppressive drug therapy is an appropriate treatment.

Macular development in the premature infant.

To classify the ophthalmoscopic appearance of the developing macula, I performed retinal examinations on 129 premature neonates. In normal infants, the classification ranged from 34 weeks of gestational age when pigment was first evident in the macula, through the development of the annular ring reflex of the macula and foveolar reflex, to a mature (adult-appearing) macula at 42 weeks. This sequence allowed the observer to estimate the gestational age of the older premature neonate from the appearance of the macular area. Babies who had, or subsequently developed, retinopathy of prematurity showed a statistically significant two-week delay in macular development in the later stages. This may be the first evidence of a direct macular insult in retinopathy of prematurity.

The transconjunctival oxygen monitor.

The transconjunctival oxygen monitor, mounted on a polymethylmethacrylate conformer, continuously measures the tissue oxygen tension of the palpebral conjunctiva. It is preferable to transcutaneous monitors because it requires no heat and correlates arterial oxygen in cerebral blood flow by monitoring a tissue bed vascularized by the internal carotid artery. We used it on 19 adult patients. The monitor was valuable in correlating arterial oxygen in hemodynamically compromised and uncompromised patients. However, the measurements decreased abruptly when the conjunctival temperature fell below 33 C in the compromised patients. The only ocular complications were conjunctival chemosis and mild punctate keratopathy in some patients; these resolved within 48 hours. This device may be useful in monitoring tissue oxygen tensions in critically ill patients and neonates at risk for retinopathy.

The pupils of term and preterm infants.

We studied the pupils of 100 term and preterm infants between 26.5 and 46 weeks' postconceptual age. The mean (+/- S.D.) pupil diameter in a dark environment (less than 10 foot-candles of illumination) was 3.6 mm (+/- 0.9). Anisocoria of 0.5 to 1.0 mm was found in nine infants. The pupils did not consistently respond to 600 foot-candles of light before 32 weeks' postconceptual age, but responded increasingly thereafter. This progressive light response correlated significantly with postconceptual age, weight, Apgar scores, and corneal diameter (P less than .01). In the perinatal period, neurologic or radiologic examination may be warranted if the pupil diameter in a dark environment is less than 1.8 mm or greater than 5.4 mm or if the pupils do not respond to light challenge after 31 weeks' postconceptual age.

Ocular signs of cocaine intoxication in neonates.

We examined 13 cocaine-intoxicated neonates, proven by urine assay, by slit lamp and found that most had iris blood vessel abnormalities. Using an iris vascularity scale that ranged from Grade 0 with no visible vessels to Grade 4 with dilated and tortuous vessels, we found that the intoxicated infants had increased grades in the iris periphery and collarette (P less than .02) as compared to 36 control newborns who had no cocaine in their urine. Infants with dilated or tortuous iris vessels were more likely to be intoxicated by cocaine (P less than .01). The presence of dilated or tortuous iris vessels in a neonate should signal the physician to rule out cocaine intoxication.

The fixed and dilated pupils of premature neonates.

We examined on a weekly basis the pupils of 30 preterm infants. In relative darkness (less than 10 foot-candles [ft.-c.] of illumination), the pupils measured a mean of 4.7 mm in the youngest infants (26 weeks' postconceptional age) when the corneal diameter was 7.0 mm. The pupils became progressively smaller, reaching 3.4 mm at 29 weeks' postconceptional age (P less than .001). The pupils did not constrict to the stimulating light (600 ft.-c.) until a mean of 30.6 weeks' (+/- 1 week) postconceptional age. Mydriasis should not be considered indicative of a central nervous system disorder, and a pupil unresponsive to light should not be considered suggestive of blindness until a preterm infant reaches at least 32 weeks' postconceptional age.

Use of the HARK autorefractor in children.

PURPOSE: We investigated the reliability, accuracy, and repeatability of an autorefractor with the capability of over-refracting and measuring visual acuity for use in children in a prospective study. METHODS: Before and after cycloplegia, 68 children (mean +/- SD age, 10 +/- 3 years, range 5-16 years) underwent autorefraction twice with the HARK 599 Autorefractor (Humphrey Instruments Inc., San Leandro, CA), subjective over-refraction through the HARK autorefractor, and subjective refraction using a phoro-optometer. After cycloplegia, retinoscopy was performed. Results are reported for one eye (left) of each child. RESULTS: For 68 eyes of 68 children, before and after cycloplegia, correlation coefficients (R) for autorefraction reproducibility exceeded 0.95 for all comparisons of sphere and cylinder. R for spherical values for autorefraction vs. over-refraction was 0.93 and vs. subjective refraction 0.83 before cycloplegia and 0.94 and 0.97 after cycloplegia. Comparing values before and after cycloplegia, autorefraction, over-refraction, and subjective refraction, the data correlated > 0.81 for sphere and 0.75 to 0.87 for cylinder. Cycloplegic retinoscopy compared with autorefraction, over-refraction, and subjective refraction had R > 0.86 for sphere and cylinder for all comparisons except one. Cycloplegia increased the proportion of spherical equivalent values within 0.625 D of the subjective refraction from 41 of 68 eyes (61%) for auto- and over-refraction to 64 (94%) and 51 (75%) of the 68 eyes, respectively. A visual acuity of 20/30 or better was produced in 50 of 68 (73%) eyes with automated refraction before and after cycloplegia and in 62 (92%) with subjective refraction before cycloplegia and subjective refraction and retinoscopy after cycloplegia. Subjective over-refraction did not significantly improve the visual acuity. CONCLUSIONS: In children, HARK autorefraction improved in accuracy, when compared to subjective refraction, and the level of visual acuity improved after cycloplegia. Over-refraction through the instrument did not improve the results before or after cycloplegia.

The effect of anterior transposition of the inferior oblique muscle.

The effect of anterior transposition of the insertion of the inferior oblique muscle was compared with the results from conventional inferior oblique muscle recession in 50 patients. Even though both groups of patients had a similar degree of overaction preoperatively, postoperative inferior oblique muscle action was weaker (P < .01) and upgaze more limited P < .01) in the anterior transposition group. These data suggest that anterior transposition serves to convert the inferior oblique muscle from an elevator to a depressor on attempted elevation. Because anterior transposition is such a powerful weakening operation, we suggest that it be reserved for patients with moderate to severe inferior oblique muscle overaction. To avoid postoperative hypotropia in upgaze, anterior transposition should be performed in both eyes for bilateral inferior oblique muscle overaction and not unilaterally.

Occlusive retinal arteriolitis with neovascularization.

A 34-year-old white woman who had used oral contraceptives for six years showed an occlusive bilateral retinal arteriolitis that resulted in a branch arteriolar occlusion in the right eye and retinal neovascularization. Three years later, we observed active arteriolitis in the left eye with successive occlusion of several branch arterioles. The disease has shown spontaneous remissions and exacerbations. An extensive medical evaluation revealed only old pulmonary granulomatous disease and an elevated sedimentation rate in association with exacerbations of the arteriolitis.

PIP: A case study of a woman who developed occlusive retinal arteriolitis with neovascularization while taking oral contraceptives (OCs) is report ed. After admission to the hospital, permanent discontinuation of OCs, and extensive testing, the only abnormal findings were an elevated sedimentation rate, a positive PPD and previous pulmonary scarring. The patient had been using OCs for 6 years prior to the onset of symptoms. Thus, the association of OC use with arteriolitis with neovascularization is unclear in this case.

Posterior fixation sutures: a revised mechanical explanation for the fadenoperation based on rectus extraocular muscle pulleys.

PURPOSE: To determine the effect of the rectus extraocular muscle pulleys on the fadenoperation, an operation designed to fixate the posterior muscle belly to the underlying retroequatorial sclera. METHODS: First, duction into the field of action of the operated-on muscle was quantified retrospectively after fadenoperation. Magnetic resonance imaging was then performed prospectively after surgery to verify anatomic changes. Forced duction testing was performed prospectively during surgery before and after faden placement. Finally, computed tomography in a cadaver containing radiographic markers was performed prospectively to determine the effect of fadenoperation on the position of the medial rectus insertion relative to its pulley. RESULTS: Mean maximum adduction after medial rectus fadenoperation was 18 degrees (range, 10 to 25 degrees; 13 eyes). Fadenoperations combined with large medial rectus recessions restricted adduction more than fadenoperations combined with smaller recessions (P = .019), but even fadenoperations without recessions substantially restricted adduction. Mean maximum abduction after lateral rectus fadenoperation was 40 degrees (range, 25 to 45 degrees; four eyes). Axial magnetic resonance imaging in two eyes demonstrated a smaller loss of muscle tangency to the globe during contraction than predicted by geometric models. Forced ductions in nine patients performed immediately after faden placement demonstrated a new mechanical restriction to duction toward the operated-on muscle. Cadaveric computed tomographic scans demonstrated posterior displacement of the medial rectus pulley during adduction after fadenoperation. CONCLUSIONS: Posterior fixation sutures do not significantly decrease muscle torque during contraction. Because posterior fixation sutures posteriorly displace the pulley sleeve during duction toward the operated-on muscle, the mechanical restriction after surgery probably represents the force deforming the pulley. This mechanical restriction may account for the limitation in duction seen after fadenoperation.

Source of the conjunctival bacterial flora at birth and implications for ophthalmia neonatorum prophylaxis.

To understand better the source of conjunctival bacteria in neonates, we studied 106 infants immediately after birth before any eyedrops were applied. The 50 infants delivered by cesarean section had significantly fewer species (0.50 +/- 0.85 vs 1.84 +/- 1.33) and colony forming units (272 +/- 1,019 vs 1,790 +/- 3,779) cultured per subject than the 56 infants delivered vaginally. In infants delivered by cesarean section within three hours of membrane rupture, 24 of 30 (80%) of the conjunctival cultures were sterile, while the rest bore a few cutaneous bacteria (0.23 +/- 0.50 species and 2 +/- 9 colony forming units per subject). The conjunctivae of infants delivered vaginally bore significantly more bacteria characteristic of vaginal flora: microaerophilic as Lactobacillus or truly anaerobic as Bifidobacterium. Neonates delivered by cesarean section more than three hours after membrane rupture showed a bacteriologic flora mixture quantitatively and qualitatively midway between those two groups. Infants delivered by cesarean section within three hours of membrane rupture may not need prophylactic eyedrops because of the type and scarcity of conjunctival bacteria.

The effect of povidone-iodine solution applied at the conclusion of ophthalmic surgery.

PURPOSE: Povidone-iodine 5% solution decreases the incidence of postoperative endophthalmitis when used on the eye for preoperative preparation. We sought to determine whether it also minimized conjunctival bacterial flora immediately after surgery by preventing bacteria present on the surface of the eye from entering surgical wounds. METHODS: In 42 eyes of 40 patients, at the conclusion of surgery, on an alternating basis, each patient received either a drop of a broad-spectrum antibiotic solution (polymyxin B sulfate-neomycin sulfate-gramicidin) or a 5% povidone-iodine solution in the operated-on eye. Bacterial cultures were taken before and after surgery and 24 hours later. The 38 unoperated-on eyes in the unilateral cases served as control eyes. RESULTS: Relative to the control group, povidone-iodine was effective in preventing an increase in the number of colony-forming units (P = .035), while the antibiotic was not. At 24 hours after surgery, the species count was lower in the eyes receiving povidone-iodine than in the antibiotic-treated eyes (P = .034) and was increased in the antibiotic group since the completion of surgery (P = .013), but was lower in the povidone-iodine and antibiotic groups than in the control eyes for both groups (P < .01). CONCLUSIONS: Povidone-iodine 5% solution applied to the eye at the conclusion of surgery was more effective at minimizing the number of colony-forming units and species for the first postoperative day than was a broad-spectrum antibiotic. While not true for the antibiotic, the antimicrobial effect of povidone-iodine lasted for at least 24 hours after the completion of surgery.