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PubMed2006

Bioptics: where do things stand?

PURPOSE OF REVIEW: Bioptics treats complex refractive errors by combining refractive techniques with different mechanisms of action, usually using an intraocular implant (a phakic or pseudophakic intraocular lens) followed by a corneal procedure (laser ablation, intrastromal implant). RECENT FINDINGS: In myopia and hyperopia, bioptics with phakic intraocular lenses or refractive lens exchange and subsequent excimer laser yields improved predictability and unchanged safety, compared with sole intraocular lens surgery. Complications are related mainly to intraocular lenses. In keratoconus and pellucid marginal degeneration, intracorneal rings have been successfully combined with phacoemulsification or with phakic intraocular lenses in a limited number of eyes. In the author's series, angle-supported phakic intraocular lenses were implanted in 12 eyes to correct a mean regression of -8 D after excimer laser (reverse bioptics), achieving a mean spherical equivalent of -0.3 D, mean best spectacle-corrected visual acuity of 0.7, and mean uncorrected visual acuity of 0.5, with 83% of eyes within 0.5 D of spherical equivalent. SUMMARY: Bioptics improves vision and halos and adds no particular risks to phakic or pseudophakic intraocular lens implantation in either myopia or hyperopia. Reverse bioptics, with phakic intraocular lenses or refractive lens exchange, can be used to correct regressed corneal surgery.

Cornea↗
PubMed2005

Glucagon- and secretin-related peptides differentially alter ocular growth and the development of form-deprivation myopia in chicks.

PURPOSE: Exogenous glucagon inhibits the induction of myopia in chicks, but the endogenous peptide and receptor that regulate eye growth are unknown. The purpose of this study was to determine which peptides and receptors in the glucagon-secretin family play a role in the control of ocular growth. METHODS: The effect of intravitreally injected peptides on the development of form-deprivation (FD) myopia and on the growth of eyes with unrestricted vision was determined by refraction and A-scan ultrasonography. Chicks received three injections, one every 48 hours, of secretin-related peptides (porcine secretin, human peptide histidine-isoleucine-amide-27, vasoactive intestinal peptide [VIP], VIP fragment 6-28, or pituitary adenylate cyclase-activating polypeptide; 10(-8)-10(-4) M in 20 microL) or five injections of proglucagon-derived peptides (human glucagon, oxyntomodulin, miniglucagon, or glucagon-like peptide [GLP]-2 or chicken GLP-1). Immunohistochemistry was used to detect proglucagon-derived peptides in the eye. RESULTS: Secretin-related peptides had no effect on FD myopia, whereas some proglucagon-derived peptides did. Both glucagon and oxyntomodulin dose-dependently inhibited development of myopia, primarily by inhibition of vitreous chamber elongation (EC(50) = 10(-4) M and 10(-5.5) M, respectively). GLP-1 increased deprivation-induced myopic refractive error by altering anterior chamber development. None of the peptides significantly affected refractive error in eyes with unrestricted vision, although changes in anterior and posterior eye growth were observed in response to glucagon, oxyntomodulin, GLP-1, and miniglucagon. Immunoreactivity for miniglucagon and GLP-1 was colocalized in glucagon-immunoreactive amacrine cells. CONCLUSIONS: Prevention of experimental myopia by exogenous glucagon is mediated by receptors selective for glucagon and oxyntomodulin, indicating that glucagon-like peptides and receptors are probable endogenous retinal regulators of the development of myopia.

Animals↗
PubMed1993

Ocular sequelae in premature infants.

OBJECTIVE: The authors report on the incidence of myopia and strabismus at 12 and 24 months postterm in a cohort of 190 premature infants with birth weights of less than 1251 g born in 1986 and 1987. METHODS: The neonatal and follow-up eye charts of a cohort of 190 premature infants were retrospectively reviewed. All 138 children who survived the neonatal period had at least one eye examination between day 28 and 42 of life that documented the presence and staging of retinopathy of prematurity (ROP) according to the International Classification of ROP. No infants received cryotherapy. Eye examinations conducted at 12 and 24 months postterm included assessment of vision, fundus, ocular motility, anterior segment abnormality, and refractive error. Eyes were refracted using cycloplegic retinoscopy. Strabismus was detected using the Hirschberg and cover tests. Eye reports were available for 80% (n = 110) at 12 months and 36% (n = 50) at 24 months. RESULTS: Fifty-three percent of the cohort exhibited ROP in the neonatal period; 12% of these progressed to stage 3 or 4 ROP. Myopia was observed in 16% (18/110) of the cohort at 12 months of age; 4.5% (5/110) measured more than 4.0 diopters of myopia. Children with birth weights of less than 751 g were 3.2 times more likely than those with birth weights between 751 and 1000 g and 10 times more likely than those with birth weights between 1001 and 1250 g to develop myopia in the first year of life. The likelihood of myopia at 12 months doubled with each increment in ROP stage. Of the 50 children reexamined at 24 months postterm, more than 80% demonstrated deteriorating vision. The incidence of myopia increased to 38% (19/50) overall, with 24% (12/50) of the cohort showing severe myopia. Astigmatism and anisometropia were highly correlated with severe myopia. Strabismus was seen with increasing frequency through the second year of life. All children with grade III or IV intraventricular hemorrhage in the neonatal period developed esotropia. CONCLUSION: This study emphasizes the significant roles of low birth weight, ROP, and intraventricular hemorrhage in the development of myopia and strabismus. Follow-up to 2 years of life is recommended given the demonstrated deterioration in our cohort.

Anisometropia↗
PubMed1977

Refraction as a basis for screening children for squint and amblyopia.

+2-00 to +2-75 dioptres of spherical hypermetropia in the more emmetropic of a pair of eyes is significantly associated with esotropia (P less than 0-001) and the presence of amblyopia (P less than 0-01). Anisometropia is not significantly associated with esotropia (P = 0-31) unless there is spherical hypermetropia of +2-00 dioptres or more in the more emmetropic eye (P less than 0-001). Hypermetropic anisometropia of +1-00 DS or +1-00 D.Cyl. is associated with the presence of amblyopia (P less than 0-001). In the absence of esotropia there is also a significant association between the amount of anisometropia and the initial depth of amblyopia (P less than 0-01). The additional presence of esotropia increases the depth of amblyopia further (P less than 0-05) but not the incidence of amblyopia (P greater than 0-30). The level of significance of the association of refractive errors with squint/amblyopia was itself significantly higher (P less than 0-01) than that between a family history of squint or "lazy eye" on the one hand and squint and/or amblyopia on the other hand. 72 +/- 3% of all cases of esotropia and/or amblyopia in this sample of children had a refractive error of +2-00 DS or more spherical hypermetropia in the more emmetropic eye, or +1-00 D. or more spherical or cylindrical anisometropia. Since there is a close association between the refraction and how, when, and whether a child presents with squint and/or amblyopia, it would seem reasonable to reconsider refraction as a basis for screening young children for visual defects.

Amblyopia↗
PubMed1988

Accommodative esotropia following surgical correction of congenital esotropia, frequency and characteristics.

This study was undertaken to look at the development of accommodative esotropia, which occurs following the surgical correction of congenital esotropia. A retrospective review was done on all congenital esotropia patients operated on by one of the authors from 1974 through mid-1984. The criterion of a minimum of 3 years postsurgical follow-up was met by 101 patients. Of these patients, 52 developed accommodative esotropia, 25 within 3 months of surgery and 27 from 3 to 60 months after surgery. The average preoperative refractive error in the early group was +3.90 and +1.95 in the later group. The average time to develop accommodative esotropia in this group with later onset was 27 months following the initial surgery. It would appear that if the preoperative refractive error is +3.00 or more, and especially if the preoperative deviation responds to spectacles with a reduction of 15 prism diopters or more, then it is very likely that glasses will be required for accommodative esotropia very soon following surgery. There appear to be no clues as to which patients will need glasses later for accommodative esotropia.

Accommodation, Ocular↗
PubMed2005

Effects of combined cataract surgery and trabeculectomy with mitomycin C on ocular dimensions.

AIMS: To characterise changes in ocular dimensions after combined cataract operation and trabeculectomy with mitomycin C using separate incisions (combined operation). METHODS: 24 consecutive eyes that had combined operation and 16 eyes that had cataract operation alone were enrolled. The axial lengths before and after operations were determined with non-contact optical coherence biometry. The intraocular pressures (IOP), axial lengths, corneal curvatures, and the expected and observed refractive errors before and after operations were compared. RESULTS: After a combined operation, mean IOP was significantly reduced from 16.6 (SD 5.8) mm Hg to 10.9 (4.1) mm Hg (p<0.00001), and mean axial length was significantly shortened from 24.10 (0.98) mm to 23.98 (0.96) mm (p<0.00001). The mean axial length reduction after combined operation (117 (57) microm) was significantly larger than the reduction after cataract operation alone (75 (38) microm, p<0.02), and correlated significantly with the postoperative IOP (p<0.002). There was a mean with the rule surgically induced corneal astigmatism of 0.44 (0.83) dioptre by vector analysis, and a significant increase of mean keratometry reading of 0.23 (0.46) dioptre after a combined operation. However, there was no significant difference between the expected and observed refractive errors. CONCLUSIONS: Despite an alteration of the axial length and corneal curvature, the refractive outcome after a combined operation did not differ significantly from the predicted refraction.

Aged↗
PubMed2006

Intraocular lens exchange due to incorrect lens power.

PURPOSE: To evaluate patients who had intraocular lens (IOL) exchange for unexpected postoperative refractive errors, determine the sources associated with the errors, and derive an empiric approach to estimating the power for IOL exchange. DESIGN: Retrospective review of interventional case series. PARTICIPANTS: Twenty-two eyes that underwent IOL exchange for correcting unexpected refractive errors after cataract surgery with IOL implantation were reviewed. INTERVENTION: All the IOLs for IOL exchange were placed in-the-bag. The same type of IOLs was used for original IOL implantation and IOL exchange in 91% (20/22) of eyes. MAIN OUTCOME MEASURES: Uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), refraction, and reasons for IOL exchange. The equation derived from refractive change and change in IOL power was developed to calculate IOL power for exchange. RESULTS: Of the 22 cases, the identified reasons were keratometry errors in 5 (23%) and incorrect axial length (AL) determination in 3 (14%). In 3 other cases, a wrong IOL was implanted. After IOL exchange, 82% (18/22) of eyes were within +/-0.50 diopters (D) and 86% (19/22) within +/-1.00 D of emmetropia. Uncorrected visual acuity was 20/40 or better in 82% of eyes, and BSCVA was 20/40 or better in 95% (21/22) of eyes. The correlation between change of refraction and IOL power was significant (P<0.002). CONCLUSIONS: Among the identified causes, incorrect corneal power determination was the most frequent reason for incorrect IOL power implantation, followed by error in AL measurement and inserting a wrong IOL. The pre-exchange refraction can be used theoretically to calculate the IOL power for exchange.

Cataract Extraction↗
PubMed2003

Too much or too little: neonatal ocular misalignment frequency can predict later abnormality.

BACKGROUND: 214 orthoptists' infants have been followed for up to 15 years, relating neonatal misalignment (NMs) and first convergence onset to later childhood ocular abnormalities. NMs are shown in a companion paper to reflect the onset of first convergence, but if frequent or absent may predict a higher risk of refractive error and esodeviation. METHODS: In a prospective postal survey, orthoptist mothers observed their own infants during the first months of life and regularly reported ocular behaviour and alignment, visual development, and any subsequent ocular abnormalities. RESULTS: Later strabismus and refractive error were less common in infants who showed NMs occasionally compared with those who never or frequently did. There was a significant linear trend for fewer ocular abnormalities to be found in children with more frequent NMs (p<0.001). Hypermetropes were later to show first convergence than emmetropes or myopes (p = 0.006) CONCLUSIONS: NMs usually reflect an emerging and normally developing vergence system. This study suggests that delayed onset of convergence (and lack of NMs) is associated with later defects, especially hyperopia. Possible causal relations are discussed.

Age Factors↗
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↗
PubMed2004

The ocular manifestations of Weissenbacher-Zweymuller syndrome.

PURPOSE: Weissenbacher-Zweymuller syndrome (WZS) is an autosomal recessive disorder of delayed skeletal maturation. Its characteristic features include rhizomelic dwarfism with metaphyseal and vertebral changes. It has been challenged whether WZS is a part of the spectrum of Stickler syndrome. We report ocular findings in the largest ever-presented series of patients with WZS. METHODS: Patients underwent a paediatric examination, including assessment of growth and development, genetic work-up and X-ray of vertebra and long bones. All had a complete ophthalmic examination, cycloplegic refraction, and face and body photography. RESULTS: All patients had hypertelorism and protruding eyes. Four patients had refractive errors necessitating optical correction ranging from +3 to -8 D. Two patients had strabismus. None had vitreoretinal degeneration, glaucoma, or cataract. CONCLUSIONS: Ocular manifestations of WZS differ from those in Stickler syndrome, indicating that the two likely represent distinct clinical entities. Strabismus and various refractive errors often accompany WZS. An ophthalmologist should follow children with this disorder from an early age to prevent amblyopia.

Adolescent↗
PubMed1986

Mass screening of children for strabismus or ametropia with two-flash photoskiascopy.

UNLABELLED: 169 non-selected 1-5 year-old children (338 eyes) were screened by two-flash photoskiascopy with an autofocus camera for strabismus, high anisometropia and high ametropias without cycloplegia. The photography was performed by nurses or technicians and the photographs were analyzed by an optician. The sensitivity of the method for the refractive errors was tested with an optical demonstration eye. FINDINGS: 5 esotropias, 1 exotropia, 1 straight-eyed hypermetropic anisometropia of 4 diopters; 1 false positive high hyperopia (of +2.5 diopters) of both eyes. The examination of the photographs showed slight refractive errors in 33 cases (66 eyes; 19.5%): two of them of symmetrical myopia of -1.0 and -1.75 diopters and 31 of symmetrical hyperopia of +0.25 to +4.25 diopters in retinoscopy. 128 cases (256 eyes; 76%) were normal on the photographs. Of these, 37 non-selected cases (74 eyes) were checked clinically and were symmetrical cases of -1.0 to +3.25 diopters on retinoscopy. No false negative cases appeared among these control cases. 2,4% of the photographs failed technically or because of noncooperation of the children. Two-flash photoskiascopy, performed by technicians or nurses provides a valuable tool for mass screening of infants for strabismus and/or ametropia causing amblyopia.

Child, Preschool↗
PubMed1984

Occlusion amblyopia secondary to a mixed capillary-cavernous hemangioma.

We report a case of amblyopia that developed in an infant and was secondary to occlusion of the visual axis by a capillary-cavernous hemangioma. In addition to occlusion amblyopia, hemangiomas can cause astigmatic and myopic refractive errors, which usually persist throughout life. Indications for treatment and therapeutic modalities are discussed. Patients with cavernous and/or capillary hemangiomas of the periorbital region need ophthalmologic consultation and close follow-up during the first year of life. Therapy should be started promptly if growth of the hemangioma threatens to occlude vision or induce refractive error.

Amblyopia↗
PubMed1995

Repeatability of subjective and objective refraction.

Although several studies have examined the repeatability of objective refraction, data concerning the repeatability of subjective refraction under masked conditions, i.e., where the examiner is unaware of the refractive results, are limited. Accordingly, the present study compared the variability of both subjective and objective refractive techniques. Refractive error was measured in 12 subjects on 5 separate occasions. Conventional subjective procedures were used, with the exception that the sphere power scale on the phoropter was covered so that the examiner was unaware of the final result. Objective measurements were obtained using a Canon Autoref R-1 infrared autorefractor. The standard deviation (SD) of the five examinations was calculated for each individual and the mean values for the population sample determined. The mean SD's for the subjective and objective techniques were +/- 0.14 and +/- 0.18 D, indicating 95% confidence limits of +/- 0.27 and +/- 0.35 D, respectively. It is concluded that with either assessment technique, a change in refractive error of at least +/- 0.50 D should be adopted as the minimum significant shift in refractive status.

Adult↗
PubMed2005

Comparison of the long-term clinical results of hydrophilic and hydrophobic acrylic intraocular lenses.

This study was performed to compare the incidence of posterior capsular opacity (PCO) and refractive errors between hydrophilic (ACR6D, Corneal) and hydrophobic (MA60BM, AcrySof) acrylic intraocular lenses (IOLs) over a 3-year follow-up after phacoemulsification surgery. The patients with AcrySof implanted in one eye and Corneal in the other eye were categorized as Group 1 (n=28), while those with one or both eyes implanted with IOLs of the same kind were categorized as Group 2 (AcrySof, n=90; Corneal, n=95). Refractive errors were evaluated at 3 months and 3 years postoperatively. The incidence of visually significant PCO was investigated 3 years postoperatively. Postoperative refractive values at 3 months were not significantly different between the two groups. However, refractive values at 3 years were significantly different between two IOLs in both groups [AcrySof -0.37+/-0.43D, Corneal -0.62+/-0.58D in Group 1 (p=0.04); AcrySof -0.38+/-0.52, Corneal -0.68+/-0.54 in Group 2 (p<0.01)]. The incidence of visually significant PCO was 14% and 32% in Group 1, and 13% and 28% in Group 2, for the AcrySof and Corneal implants, respectively. The incidence of visually significant PCO of hydrophilic acrylic IOLs was higher than that of hydrophobic acrylic IOLs in the 3-year follow-up. The postoperative 3-year refractive value of Corneal showed myopic shift.

Acrylic Resins↗
PubMedDate not supplied

Axial length estimation in strabismic patients.

BACKGROUND: Previous studies have indicated that axial length determination is important in strabismic patients for defining the limit for a safe maximum recession of the medial rectus. Also, the response to strabismus surgery may be, in part, a function of axial length. We previously published a formula for predicting axial length based on age and refractive error; however, its accuracy has not been tested in a patient population that is different from the one used to generate the formula. The purpose of this study is to test a formula for estimating axial length, given age and refractive error, in a population that is different from that from which it was generated. METHOD: We measured axial length using A-scan ultrasonography in 163 consecutive patients undergoing strabismus surgery. Twenty-nine patients were younger than 18 months of age; 134 patients were between 18 months and 10 years of age. We compared the measured axial length determination with the axial length value estimated by a formula generated from our previous published series. RESULTS: For patients younger than 18 months of age, the equation estimated axial length within 0.5 mm in 41.4% of patients, within 1.0 mm in 79.3% of patients, and within 1.5 mm in 93.1% of patients. For patients between 18 months and 18 years of age, the formula estimated axial length within 0.5 mm in 37.3% of patients, within 1.0 mm in 73.1% of patients, and within 1.5 mm in 87.3% of patients. CONCLUSIONS: The formula may be useful for the strabismus surgeon in estimating axial length when A-scan ultrasonography is not available in an operating room setting, particularly in congenital esotropes who require larger recessions in small eyes. If, however, A-scan ultrasonography is available, it is preferable to using the formula. The formula is not sufficiently accurate for use for calculating intraocular lens power.

Child↗
PubMed1989

[Calculation of the implant: is it a useless luxury?].

Analysis of the means by which accuracy of intraocular lens power calculation could be improved with theoretical and linear regression formulas. The postoperative refractive errors with the lenses selected by the surgeon were compared with those observed with the emmetropic calculated power lenses and with a standard 20 diopters lens. A consecutive series of 100 eyes with less than 4.50 diopters of pre-operative myopia or hypermyopia, is evaluated. Postoperative refractive errors are out of the range -4; +4 diopters in 6% for standard lens, 4% for actually implanted lens, and 1% for emmetropic power calculated lens.

Algorithms↗
PubMed1993

Causative factors in unilateral giant papillary conjunctivitis.

Giant papillary conjunctivitis (GPC) is usually a bilateral disease. However, in a small number of cases, GPC can be manifested as a unilateral, or a markedly asymmetrical disease in patients wearing bilateral contact lenses. We reviewed the clinical records of 148 patients with GPC to determine the incidence of unilateral GPC and its causative factors. Specifically, charts were reviewed for data on refractive error, keratometry, lens fit, lens care, lens replacement, and the presence or absence of associated ocular abnormalities (dry eyes, blepharitis, previous injury, or surgery). Fourteen patients with unilateral or markedly asymmetrical disease were identified. Overall, no statistically significant difference was found in lens care, refractive error, or keratometric measurements in the affected and unaffected eyes. While not statistically significant, infrequent lens replacement appears to be an important factor in the development of unilateral GPC. Three patients had a history of wearing an older lens in the GPC eye. Two patients were found with unilateral meibomian gland dysfunction involving the affected eye, and one patient had undergone surgery on the affected eye. No causative factor was identified in eight cases.

Adolescent↗
PubMed2001

Cycloplegic refractions in healthy children aged 1 through 48 months.

OBJECTIVES: To provide a description of refractive errors in healthy, term-born children, aged 1 through 48 months, and to test the hypotheses that spherical equivalent becomes significantly less hyperopic and less variable with increasing age. METHODS: Following a prospective, cross-sectional design, cycloplegic retinoscopy was used to measure the refractive error in both eyes of 514 healthy, term-born children in 12 age groups. Three hundred were aged 12 months or younger. Spherical equivalent and cylindrical power and axis were analyzed as a function of age. Prediction limits for spherical equivalent were calculated. RESULTS: Spherical equivalents of right and left eyes did not differ at any age. Hyperopia declined significantly with increasing age. The variability in spherical equivalent also decreased significantly with age. Cylindrical error of 1 diopter or more was found in 25% of the children; the proportion with astigmatism was highest in infancy and then waned. Myopia and anisometropia were rare, occurring in 3% and 1% of the sample, respectively. CONCLUSIONS: Significant declines in hyperopia and variability of spherical equivalent appear to be features of emmetropization. The normal prediction limits provide guidelines against which data from individual patients can be compared.

Age Distribution↗