Biomedical subjects

J M Holmes

Publications and source records attributed to J M Holmes.

79 records · Page 5Linked to original sources

PubMedDate not supplied

Vernier acuity cards: a practical method for measuring vernier acuity in infants.

The feasibility of a practical preferential looking technique, similar to Teller acuity cards, was investigated for the assessment of vernier acuity in preverbal infants. Forty-two infants ages 1 to 13 months were tested with cards having vernier offsets of 2 to 64 minutes of arc and spatial frequencies of 0.25 to 2.0 cycles per degree. All infants showed a robust preferential looking response to the largest vernier offsets. Vernier thresholds decreased with age from 64 minutes of arc at 1 month to 4 minutes of arc at 13 months. Smaller vernier offsets were more readily detectable when embedded in higher spatial frequency gratings. Vernier acuity can be assessed in preverbal infants using a preferential looking technique similar to that employed with the Teller acuity cards. Vernier acuity is known to be more sensitive to amblyopia than grating acuity; therefore, this technique may prove useful in the assessment of amblyopia.

Humans↗

PubMedDate not supplied

Recovery of phorias following monocular occlusion.

Fourteen nonstrabismic volunteers were monocularly patched for 2 and 24 hours in separate experiments. Horizontal and vertical phorias were measured at 6 m and 30 cm, at 30-second intervals, for at least 30 minutes, following removal of the patch. After 24 hours of monocular occlusion, the initial change from baseline at 6 m ranged from 9.5 prism diopters exo to 7 delta eso and 6.5 delta hyper to 3 delta hypo. At 30 cm, the initial change ranged from 7.5 delta exo to 4 delta eso and 1 delta hyper to 1 delta hypo. In all but three subjects, phorias returned to within 2 delta of baseline by 3 minutes, and in all subjects by 25 minutes. After 2 hours of monocular occlusion, the range of initial change from baseline was similar to 24 hours of occlusion, but all phorias returned to within 2 delta of baseline by 2.5 minutes. Therefore, we suggest that ocular alignment should not be routinely measured within 3 minutes of removing a patch. If patched for 24 hours, a few individuals will require up to 25 minutes for stabilization of their deviation. Further studies might address these effects in patients with subnormal fusion and stereopsis.

Adult↗

PubMedDate not supplied

Randomized clinical trial of surfactant prophylaxis in retinopathy of prematurity.

Prophylactic lung surfactant is commonly used to reduce the severity of neonatal respiratory distress syndrome in premature infants. There is disagreement in the literature regarding the effect of prophylactic lung surfactant on the incidence of retinopathy of prematurity (ROP). Sixty-four infants, gestational age 23 to 32 weeks, birth weight 610 to 1250 g, were randomized to receive either intratracheal bovine surfactant prophylaxis or air control, at our institution, as part of a national double-masked multicenter trial. Forty-eight of these infants survived and underwent complete ophthalmologic examinations by a single masked examiner. ROP data were gathered retrospectively. ROP developed in 19 of the 23 (83%) who received surfactant and 15 of the 25 (60%) controls (P = .1). Analysis of the worst stage of ROP for each infant also revealed no difference between the surfactant and control groups (P = .4). Our retrospective analysis of ROP data in a prospective double-masked randomized study revealed no significant effect of surfactant on the incidence or severity of ROP.

Double-Blind Method↗

PubMedDate not supplied

Comparison of grating and Vernier acuity in infants with developmental delay.

BACKGROUND: Grating acuity measured by Teller cards is mildly reduced in children with developmental delay. Vernier acuity, the ability to detect offsets, also can be measured, but has not been studied in children with developmental delay. METHODS: In a prospective cross-sectional pilot study, 12 nonverbal children with developmental delay established by pediatric assessment of developmental milestones were tested binocularly with vernier and Teller cards. Ages ranged from 4 to 24 months. Vernier offsets ranged from 2 to 64 minutes of arc. RESULTS: All children were testable with Teller acuity cards. Binocular grating acuity ranged from 1.7 to 7.4 cpd (median, 1.0 octaves below normal). Binocular vernier acuity ranged from unrecordable to 8 minutes of arc (median, "unrecordable"). Only four of the 12 children demonstrated a measurable vernier acuity. Normal children of this age have a vernier acuity of 2 to 16 minutes of arc measured by this technique. CONCLUSION: The response to vernier acuity cards appears to be more severely degraded by developmental delay than the response to Teller cards.

Child, Preschool↗

PubMedDate not supplied

Duane syndrome associated with oculocutaneous albinism.

A 5-year-old female presented with signs of Duane's retraction syndrome and oculocutaneous albinism. Duane's syndrome is associated with anomalous innervation of the lateral rectus by the oculomotor nerve. Oculocutaneous albinism is associated with an increased proportion of crossed retinal ganglion fibers at the chiasm. Because Duane's syndrome and oculocutaneous albinism are both examples of ocular miswiring, a common mechanism is suggested.

Albinism, Oculocutaneous↗

PubMedDate not supplied

Optimum timing of postoperative adjustment in a rabbit model of adjustable suture strabismus surgery.

Strabismus surgeons disagree on the optimum timing of the postoperative adjustment in adjustable suture surgery. We compared the peak force necessary for adjustment at various postoperative times using a rabbit model. Twenty-four eyes of 12 rabbits underwent a superior rectus recession of 5 mm using a standard adjustable suture technique. The eyes were randomized to adjustment at 15 minutes, and at 6, 24, and 48 hours postoperatively. The peak force required to advance the muscle 3 mm was measured using a strain gauge. During each adjustment, the peak force was noted to be that required for initial disinsertion of muscle from sclera. The mean peak force required was 14 +/- 5 g at 15 minutes, 37 +/- 10 g at 6 hours, 60 +/- 40 g at 24 hours, and 103 +/- 52 g at 48 hours. There was a significant relationship between the time of adjustment and the peak force required for adjustment (F = 7.8, P = 0.001). Post-hoc analysis showed that the peak force required at 48 hours was greater than that required at 24 hours (P = 0.04), 6 hours (P = 0.003), and at 15 minutes (P = 0.0002). The force required for adjustment at 24 hours and beyond was greater than the maximal force generated by an extraocular muscle. We therefore suggest that the postoperative adjustment should be performed within the first 24 hours.

Animals↗

PubMedDate not supplied

Infected congenital mucocele of the nasolacrimal duct.

The authors report their experience with an infant presenting with an infected nasolacrimal duct mucocele, emphasizing correlation of clinical, CT, and surgical findings. CT is the imaging modality of choice to demonstrate the triad of 1) a cystic medial canthal mass, 2) dilatation of the nasolacrimal duct, and 3) a submucosal nasal cavity mass; findings which are diagnostic of this entity. A brief review of the relevant embryology is also presented.

Humans↗