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Biomedical subjects

Michael O'Keefe

Publications and source records attributed to Michael O'Keefe.

17 recordsLinked to original sources
PubMed2006

Corneal hysteresis and intraocular pressure measurement in children using the reichert ocular response analyzer.

PURPOSE: To examine corneal hysteresis in children with normal eyes and congenital glaucoma and assess intraocular pressure (IOP) measurement with the Reichert Ocular Response Analyzer (RORA). DESIGN: Observational, cross-sectional study. METHODS: setting: Clinical practice. patients: Corneal hysteresis and intraocular pressure (Goldmann correlated [IOPg] and corneal compensated [IOPcc]) were recorded with RORA. IOP was also measured by Goldmann applanation tonometry. RESULTS: Mean corneal hysteresis of 12.5 mm Hg was recorded in 81 [corrected] normal eyes of 42 children. It was markedly lower (mean 6.3 mm Hg) in 11 eyes of eight children with congenital glaucoma. No correlation was found between age and corneal hysteresis (r = -0.08). IOPg did not differ significantly from Goldmann applanation tonometry (P = .27). IOPcc was statistically significantly greater than IOPg (P = .014). RORA measurement was not possible in the presence of nystagmus but was possible with applanation tonometry. Cooperation with IOP measurement was much higher with RORA (89.8%) compared with applanation tonometry (78.7%). CONCLUSIONS: Corneal hysteresis in children is similar to that reported in adults. No correlation was found with age. In the presence of nystagmus, IOP measurement was possible with Goldmann applanation tonometry but not RORA. Cooperation with IOP measurement was better with RORA than with Goldmann applanation tonometry.

Adolescent↗
PubMed2006

Higher-order aberrations in children.

PURPOSE: To quantify and characterize higher order aberrations in children and to investigate the influence of refractive error and cycloplegia. DESIGN: Observational cross-sectional study. METHODS: setting: Clinical practice. patients: One hundred sixty-two eyes of 82 children were examined. The mean age of the children was 6.7 years (range, 4 to 14 years), and the mean manifest refractive spherical equivalent was 2.39 +/- 3.35 diopters (range, -8.98 to +8.45 diopters). Aberrometry was performed with a wavefront analyzer (after cycloplegia and mydriasis with cyclopentolate 1%). Aberrometry was also conducted on a subgroup of 52 eyes of 27 children, both before and 30 minutes after the instillation of cyclopentolate 1% to investigate the effect of paralysis of accommodation. RESULTS: Mean root mean square values of total-, third-, fourth-, and fifth-order aberrations were 0.37 +/- 0.13 microm, 0.23 +/- 0.12 microm, 0.16 +/- 0.11 microm, and 0.08 +/- 0.12 microm, respectively. Mean root mean square values of total coma (Z(3)(-1), Z(3)(1), Z(5)(-1), Z(5)(1)) and total trefoil (Z(3)(-3), Z(3)(3), Z(5)(-3), Z(5)(3)) were 0.27 +/- 0.31 microm and 0.21 +/- 0.29 microm, respectively. Myopes had statistically significant greater levels of total (P = .005) and fourth order (P = .002) aberrations and Zernicke terms (Z(3)(-3), Z(3)(-1), Z(3)(3), Z(4)(-4), and Z(4)(2)) compared with hyperopes. Cycloplegia had minimal influence on higher-order aberrations. CONCLUSION: Significant levels of higher-order aberrations were found in these children. They were influenced by refractive error, because myopes had significantly greater levels compared with hyperopes. Paralysis of accommodation with cyclopentolate appeared to have little effect on higher-order aberrations.

Accommodation, Ocular↗
PubMed2006

Long-term refractive and biometric outcomes following diode laser therapy for retinopathy of prematurity.

PURPOSE: To assess the long-term refractive and biometric outcomes of diode laser-treated eyes in threshold retinopathy of prematurity (ROP). METHODS: Cycloplegic autorefraction and biometry (Zeiss IOLMaster) were performed, at a mean follow-up of 11 years, on 16 laser-treated eyes with threshold ROP and 9 comparison eyes with subthreshold untreated ROP. RESULTS: The laser-treated eyes had a mean spherical equivalent of -2.33 D with a mean astigmatic error of 1.38 D. The comparison eyes had a mean spherical equivalent of +1.07 D with a mean astigmatic error of 0.42 D. This trend toward increased myopia in treated eyes did not achieve statistical significance (p=0.08). The myopia in the laser group appeared to be slowly progressive in nature when compared with earlier refractive data for these patients. The laser-treated eyes had reduced anterior chamber depth (ACD) compared with the subthreshold eyes (p=0.02). When physiologic accommodation was inhibited by cycloplegic drops, the anterior chamber deepened by 0.13 mm in the laser-treated eyes and by 0.06 mm in the comparison eyes. This effect of accommodation on ACD did not differ significantly between the two groups (p=0.23). The laser-treated eyes and the comparison eyes did not differ significantly in terms of axial length, corneal power, corneal diameter, or lens power. However, both groups had steeper corneas, shallower anterior chambers, and shorter axial lengths when compared with historical full-term controls. CONCLUSIONS: Myopia in premature infants requiring laser treatment for ROP is associated with a shallowing of the anterior chamber and a steepening of the cornea. Physiological accommodation is not impaired by laser therapy or by severe ROP.

Accommodation, Ocular↗
PubMed2006

Paediatric aphakic glaucoma.

CONTEXT: Aphakic glaucoma is a serious, sight-threatening complication in children who remain aphakic following congenital cataract surgery. The reported incidence varies from 15% to 45% and it has a higher incidence in small eyes and in babies who undergo surgery before 4 weeks of age. Most cases take the form of open-angle glaucoma. Despite careful monitoring, diagnostic difficulties in children may lead to delayed treatment. Aphakic children require ongoing monitoring, including examinations carried out under general anaesthesia. MANAGEMENT: Contrary to earlier optimism, it is unlikely, according to current clinical information, that intraocular lenses provide protection against the development of glaucoma. It is likely that the lower incidence of glaucoma in pseudophakic eyes results from selection bias for lens insertion. Both medical and surgical treatments have a role in glaucoma management. Trabeculectomy with mitomycin C or Seton implantation (glaucoma drainage device) form the mainstay of surgical treatment. The success rate with Seton implants is better in the short term and more promising in the longer term than that of trabeculectomy. Cyclodestructive procedures play a role in refractory glaucoma. Success rates for surgery range from 14% to 44% and many children require additional medical treatment. Children with aphakic glaucoma need lifelong care. Despite our best efforts, many have poor vision, poor glaucoma control and ultimately become blind.

Aphakia, Postcataract↗
PubMed2006

Outcome of LASIK for myopia in women on hormone replacement therapy.

PURPOSE: To investigate the effect of hormone treatment on refractive and visual outcome after LASIK in women. METHODS: A retrospective review of the hospital notes of all women on hormone replacement therapy (HRT) and oral contraceptives at the time of LASIK was performed. Their refractive and visual outcomes were compared with those of women not on hormone treatment. RESULTS: At 6 months after LASIK, 20 (45%) HRT eyes and 61 (75%) control eyes had a visual acuity of > or = 20/20. Thirty-six (82%) eyes from the HRT group and 74 (91%) eyes from the control group could see > or = 20/40. A statistically significant difference was noted in both refractive and visual outcome in women taking HRT at the time of surgery in comparison to controls. Women on the oral contraceptive pill did not differ in outcome from controls. CONCLUSIONS: Women on HRT are at an increased risk of refractive regression after LASIK.

Adult↗
PubMed2005

Pseudomonas aeruginosa endophthalmitis in a preterm infant.

Bacterial endophthalmitis is rare in the neonatal period. It occurs in susceptible individuals such as preterm infants. Pseudomonas aeruginosa, a Gram-negative bacillus, has been identified as the causative organism in more than 75% of invasive neonatal eye infections. The source may be endogenous; secondary to septicemia or exogenous, including reports of nosocomial infections and those infections arising from the birth canal. We report the case of a preterm infant who developed pseudomonas endophthalmitis, septicemia, and meningitis after a corneal abrasion.

Cataract↗
PubMed2005

Central corneal thickness and corneal diameter in premature infants.

BACKGROUND: Central corneal thickness is significantly greater in full-term infants than in adults. Very little is known about corneal thickness in premature infants. METHODS: Measurements of central corneal thickness and horizontal corneal diameter were carried out in 35 premature babies (70 eyes) undergoing screening for retinopathy of prematurity. Initial measurements were taken at approximately 31 weeks gestational age and at intervals until term was reached. RESULTS: Babies born at approximately 31 weeks have very thick corneas which show a progressive and statistically significant decrease to term. Conversely, horizontal corneal diameter shows a progressive significant increase to term. A very strong inverse correlation was found between these two parameters. CONCLUSION: We demonstrate that premature infants have thick corneas and small corneal diameters. Central corneal thickness decreases dramatically from approximately 31 weeks to term and is mirrored by a significant increase in corneal diameter.

Birth Weight↗
PubMed2003

Heterozygous mutations of the kinesin KIF21A in congenital fibrosis of the extraocular muscles type 1 (CFEOM1).

Congenital fibrosis of the extraocular muscles type 1 (CFEOM1; OMIM #135700) is an autosomal dominant strabismus disorder associated with defects of the oculomotor nerve. We show that individuals with CFEOM1 harbor heterozygous missense mutations in a kinesin motor protein encoded by KIF21A. We identified six different mutations in 44 of 45 probands. The primary mutational hotspots are in the stalk domain, highlighting an important new role for KIF21A and its stalk in the formation of the oculomotor axis.

Amino Acid Sequence↗
PubMed2003

Capillary haemangioma of the eyelids and orbit: a clinical review of the safety and efficacy of intralesional steroid.

PURPOSE: To describe the presenting features, investigations, treatment and outcome of a series of patients with capillary haemangioma of the eyelids and orbit. METHODS: A retrospective analysis of 21 patients, presenting between the years 1985 and 2000. Effectiveness of treatment was determined by final visual acuity and cosmetic result. RESULTS: Lesions were more common in females and the upper eyelid was a definite site of predilection. A total of 87.5% of lesions presented within 6 weeks of birth. Intralesional steroid injections were received by 79% of patients. Amblyopia was a definite complication. No local or systemic complications were associated with intralesional steroid injection. Surgery and laser treatment were reserved for persistent lesions. CONCLUSION: Early recognition and prompt treatment with intralesional steroid prevents early occlusion amblyopia, but follow-up and management of refractive amblyopia with glasses and patching is necessary in the longer term. In this series, intralesional steroid proved to be a safe effective treatment.

Amblyopia↗
PubMed2003

Outcome of zone 1 retinopathy of prematurity.

PURPOSE: To describe the outcome in a series of patients with pre-threshold and threshold zone 1 retinopathy of prematurity. METHODS: We performed a retrospective analysis of 12 babies, 24 eyes, with zone 1 retinopathy of prematurity, treated between 1992 and 2002 with diode laser treatment. RESULTS: Ten out of the 12 babies had an unfavourable outcome. The only patients with successful anatomical outcomes were those treated before threshold disease occurred. All babies had developmental delay or neurological disability. CONCLUSION: Zone 1 retinopathy of prematurity has a poor anatomical and visual prognosis and many of the babies in our study had developmental delay and neurological disability. Earlier treatment may improve the visual outcome.

Cryotherapy↗
PubMed2002

CFEOM1, the classic familial form of congenital fibrosis of the extraocular muscles, is genetically heterogeneous but does not result from mutations in ARIX.

BACKGROUND: To learn about the molecular etiology of strabismus, we are studying the genetic basis of 'congenital fibrosis of the extraocular muscles' (CFEOM). These syndromes are characterized by congenital restrictive ophthalmoplegia affecting muscles in the oculomotor and trochlear nerve distribution. Individuals with the classic form of CFEOM are born with bilateral ptosis and infraducted globes. When all affected members of a family have classic CFEOM, we classify the family as a CFEOM1 pedigree. We have previously determined that a CFEOM1 gene maps to the FEOM1 locus on chromosome 12cen. We now identify additional pedigrees with CFEOM1 to determine if the disorder is genetically heterogeneous and, if so, if any affected members of CFEOM1 pedigrees or sporadic cases of classic CFEOM harbor mutations in ARIX, the CFEOM2 disease gene. RESULTS: Eleven new CFEOM1 pedigrees were identified. All demonstrated autosomal dominant inheritance, and nine were consistent with linkage to FEOM1. Two small CFEOM1 families were not linked to FEOM1, and both were consistent with linkage to FEOM3. We screened two CFEOM1 families consistent with linkage to FEOM2 and 5 sporadic individuals with classic CFEOM and did not detect ARIX mutations. CONCLUSIONS: The phenotype of two small CFEOM1 families does not map to FEOM1, establishing genetic heterogeneity for this disorder. These two families may harbor mutations in the FEOM3 gene, as their phenotype is consistent with linkage to this locus. Thus far, we have not identified ARIX mutations in any affected members of CFEOM1 pedigrees or in any sporadic cases of classic CFEOM.

Female↗
PubMed2002

Characterization of changes in blood vessel width and tortuosity in retinopathy of prematurity using image analysis.

Many retinal diseases are characterised by changes to retinal vessels. For example, a common condition associated with retinopathy of prematurity (ROP) is so-called plus disease, characterised by increased vascular dilation and tortuosity. This paper presents a general technique for segmenting out vascular structures in retinal images, and characterising the segmented blood vessels. The segmentation technique consists of several steps. Morphological preprocessing is used to emphasise linear structures such as vessels. A second derivative operator is used to further emphasise thin vascular structures, and is followed by a final morphological filtering stage. Thresholding of this image is used to provide a segmented vascular mask. Skeletonisation of this mask allows identification of points in the image where vessels cross (bifurcations and crossing points) and allows the width and tortuosity of vessel segments to be calculated. The accuracy of the segmentation stage is quite dependent on the parameters used, particularly at the thresholding stage. However, reliable measurements of vessel width and tortuosity were shown using test images. Using these tools, a set of images drawn from 23 subjects being screened for the presence of threshold ROP disease is considered. Of these subjects, 11 subsequently required treatment for ROP, 9 had no evidence of ROP, and 3 had spontaneously regressed ROP. The average vessel width and tortuosity for the treated subjects was 96.8 microm and 1.125. The corresponding figures for the non-treated cohort were 86.4 microm and 1.097. These differences were statistically significant at the 99% and 95% significance level, respectively. Subjects who progressed to threshold disease during the course of screening showed an average increase in vessel width of 9.6 microm and in tortuosity of +0.008. Only the change in width was statistically significant. Applying a simple retrospective screening paradigm based solely on vessel width and tortuosity yields a screening test with a sensitivity and specificity of 82% and 75%. Factors confounding a more accurate test include poor image quality, inaccuracies in vessel segmentation, inaccuracies in measurement of vessel width and tortuosity, and limitations inherent in screening based solely on examination of the posterior pole.

Algorithms↗
PubMedDate not supplied

Fundus fluorescein angiography in the screening for and management of retinopathy of prematurity.

OBJECTIVES: To describe the characteristics of fundus fluorescein angiography in retinopathy of prematurity (ROP) and to explore the possible benefits of fundus fluorescein angiography over conventional indirect ophthalmoscopy in the screening for and management of ROP. PATIENTS AND METHODS: Beginning in January 2003, 23 consecutive patients were recruited for a nonrandomized, investigational trial. Fifty-one sessions of fundus fluorescein angiography were performed as part of ROP screening. RESULTS: Fundus fluorescein angiography caused no adverse effect. Clear angiograms were easily obtained. There was delayed arm-to-eye fluorescein transit. Leakage of fluorescein was observed in all stage 2 and stage 3 ROP. The leakage resolved soon after treatment. Arteriovenous tufts were found far posterior to the ROP ridge and were a feature of severe ROP. CONCLUSIONS: Some vascular pathology observed on angiograms cannot be seen on indirect ophthalmoscopy. There was delayed arm-to-eye transit and fluorescein transit within the eyes. Fundus fluorescein angiography allows more objective assessment of disease stage and zone. Regression of ROP is clearly observed on fundus fluorescein angiography.

Birth Weight↗
PubMedDate not supplied

Pars plana lensectomy for the management of ectopia lentis in children.

BACKGROUND: Nontraumatic ectopia lentis arises from a variety of inherited disorders. It may also occur as an isolated abnormality in an otherwise healthy individual. Surgical intervention is necessary when lens subluxation causes a significant refractive error resulting in amblyopia. PATIENTS AND METHODS: We report the results of pars plana lensectomy for nontraumatic ectopia lentis in 24 eyes of 13 patients and provide data on the merits of this surgical approach. better in 17 of 22 eyes and 6/12 or better in 19 of 22 eyes. Other than contact lens-related problems, there were no perioperative or postoperative complications. CONCLUSIONS: Pars plana lensectomy is a safe, effective procedure for the management of ectopia lentis. Visual outcomes are excellent. These findings should encourage earlier surgery when indicated to prevent amblyopia and improve visual acuity.

Adolescent↗
PubMedDate not supplied

Pediatric refractive surgery.

Refractive surgery in children is controversial; it is mainly performed when conventional treatment has failed. The primary indications are anisometropic amblyopia and bilateral high myopia. The major areas of concern are unstable refraction due to ongoing growth of the eye, and long-term implications. The most popular procedures are photorefractive keratectomy or laser-assisted subepithelial keratomileusis followed by laser-assisted in situ keratomileusis. There are technical difficulties involved in performing these procedures because of smaller palpebral apertures and the need for general anesthesia in younger children. Reports of minimal haze and regression in children who have undergone photorefractive keratectomy for high myopia are of interest, as this is contrary to what occurs in adults. Additional study may result in better long-term data and further indications for refractive surgery in children.

Child↗