Refractive development in children with Down's syndrome: a population based, longitudinal study.

AIMS: To study the refractive development in children with Down's syndrome longitudinally. METHODS: An unselected population of 60 children with Down's syndrome was followed with repeated retinoscopies in cycloplegia for 2 years or more (follow up 55 (SD 23) months). Accommodation was assessed with dynamic retinoscopy. RESULTS: From longitudinal spherical equivalent values of the right eye, three main categories of refraction were defined: stable hypermetropia (<1.5 D difference between the first and last visit) (n=34), increasing hypermetropia ("hypermetropic shift"; >/=1.5 D difference) (n=11), and decreasing hypermetropia/development of myopia ("myopic shift"; >/=1.5 D difference) (n=9). Patients with anisometropia (n=6) were evaluated separately. In the stable hypermetropia group three sublevels were chosen: low (+4.0 D). An accommodation weakness was found in 55% of the children. Accommodation weakness was significantly less frequent in the stable, low grade hypermetropia group (22%) than in all the other groups (p=0.008). The frequency of astigmatism >/=1.0 D at the last visit was 57%, the direction of axis being predominantly "with the rule." All the eyes with oblique astigmatism had a side specific direction of axis; the right eyes belonging to the 135 degrees axis group and the left eyes to the 45 degrees axis group. CONCLUSION: A stable, low grade hypermetropia was significantly correlated with a normal accommodation. Accommodation weakness may be of aetiological importance to the high frequency of refractive errors encountered in patients with Down's syndrome. A striking right-left specificity in the oblique astigmatic eyes suggests that mechanical factors on the cornea from the upward slanting palpebral fissures may be a major aetiological factor in the astigmatism.

Strabismus and binocular function in children with Down syndrome. A population-based, longitudinal study.

PURPOSE: We have performed a population-based, longitudinal study on strabismus in children with Down syndrome. The aims of the study were to examine the frequency and type of strabismus, the age at onset, and the binocular potential. METHODS: An unselected population of 60 children with Down syndrome born 1988-1999 was followed with repeated examinations. Mean follow-up time was 55+/-23 months (range 24--115). The alignment of the eyes was examined using Hirschberg corneal reflex test and cover test for near fixation. To evaluate binocular function, Titmus House Fly Test and Lang's stereo test were used. RESULTS: Twenty-five patients (42%) had strabismus (21 esotropias, two exodeviations and two vertical deviations). Only one case of infantile esotropia was found, the other esotropias were acquired forms. The mean age at "onset" (e.g. when strabismus was first noticed) was 54+/-35 months. In the acquired esotropia group (n=20), 15 (75%) were associated with hypermetropia (mean spherical equivalent +4.3+/-1.7 D). Seventeen of the strabismic patients had an accommodation weakness. Eleven of the strabismus patients gave a clearly positive response to one or both stereotests. CONCLUSIONS: The majority of the Down syndrome children with strabismus have an acquired esotropia and hence a potential for binocularity. Hypermetropia and accommodation weakness are probably important factors in esotropia in Down syndrome patients.

Corneal grafting for keratoconus in mentally retarded patients.

PURPOSE: To compare the results of penetrating and non-penetrating corneal grafting procedures in mentally retarded keratoconus patients. METHODS: In the years 1974-2000 41 mentally retarded patients with keratoconus (33 with Down syndrome) were operated with corneal grafting. Mean age at operation was 36.7+/-10.8 years. Three different surgical procedures were used (no randomization): penetrating keratoplasty (n=16), lamellar keratoplasty (n=5) and epikeratophakia (n=20). In a retrospective study, the non-penetrating procedures (lamellar keratoplasty and epikeratophakia) were compared to the penetrating keratoplasties with regard to graft survival and frequency of serious complications. Mean follow-up time of all grafting procedures was 80+/-58 months. RESULTS: All cases of serious complications (irreversible rejection, wound leakage or perforation) occurred in the penetrating keratoplasty group (p=0.0005). Older age at operation (p=0.011) adversely influenced the frequency of serious complications. Overall five-year survival was 74.9%. Graft survival was not related to surgical procedure, but rather to age at operation (poorer survival in older age, p=0.012) and degree of retardation (poorer survival in patients with more severe retardation, p=0.051). CONCLUSIONS: Because of the safety and low frequency of complications, epikeratophakia is recommended as the grafting procedure of choice in the majority of mentally retarded with keratoconus. In selected cases (good cooperation, age < or =40 years, and a good peripheral corneal thickness) penetrating keratoplasty may be performed, which, if uncomplicated, often will give better functional/optical results.

Biometric measurements of the eyes in teenagers and young adults with Down syndrome.

PURPOSE: To examine ocular biometric variables in subjects with Down syndrome. METHODS: In a population-based study we have compared ocular biometric variables in a group of 47 individuals with Down syndrome (20.0+/-3.9 years) with 51 control subjects (21.0+/-4.6 years). RESULTS: A thinner cornea (0.48+/-0.04 mm vs. 0.55+/-0.03 mm, p<0.001) and higher keratometry values (46.39+/-1.95 D vs. 43.41+/-1.40 D, p<0.001) were found in the Down syndrome group than in the control group. Oblique astigmatism was commonly found in the Down syndrome individuals, showing a strong right-left specificity (right eyes' axes in the 135 degrees -meridian, left eyes' axes in the 45 degrees -meridian). The lens was thinner (3.27+/-0.29 mm vs. 3.49+/-0.20 mm) and the calculated lens power was weaker (17.70+/-2.36 D vs. 19.48+/-1.24 D) in the Down syndrome group than in the control group (p<0.001 in both cases). CONCLUSIONS: Thinning of the corneal stroma may account for the steeper cornea and the high frequency of astigmatism in Down syndrome due to lower corneal rigidity. It may also be of etiological importance to the increased incidence of keratoconus in Down syndrome.

[Corneal transplantation]. / Hornhinnetransplantasjon.

The first successful corneal transplantation was done in 1906, when the corneas of a recently deceased boy were transferred to a man blinded by an alkali burn. Since then, improved equipment, microsurgical technique and better methods for treating postoperative complications have greatly improved the prognosis of corneal grafting. Immunological reactions are less frequently seen after keratoplasty than after other types of transplantation, and the graft is also directly accessible for immunosuppressive treatment. Penetrating keratoplasty accounts for more than 95% of all corneal transplantations in Norway, the other procedures being lamellar grafting and epikeratophakia. While keratitis and macula corneae previously were the main indications for keratoplasty, keratoconus is at present the most frequent indication. The prognosis is poorer in eyes with extensive vascularization, lacking sensibility, insufficient tear secretion and marked symblepharon. Due to shortage of suitable donor tissue, the waiting lists for this type of ocular surgery are increasing.

[Adverse effects of local use of beta-blockaders in glaucoma. A literature review and a survey of reports to the adverse drug reaction authority 1986-95]. / Bivirkninger ved lokal bruk av betablokkere ved glaukom. En litteraturgjennomgang og en oversikt over spontanrapporteringer til Bivirkningsnemnda 1986-95.

The review is based on a survey of studies on adverse reactions related to topical administration of beta-blockers for glaucoma. Locally applied beta-blocking agents are partially resorbed from the nasal mucosa. Concentrations which give rise to systemic effects occur invariably. Several reports exist of congestive heart failure, arrhythmias, severe respiratory symptoms, depression, hallucinations and confusion provoked by topical use of beta-blockers, especially timolol. It is impossible to estimate from the literature how often the various adverse effects occur. One has the impression, however, that adverse effects in the pulmonary and central nervous systems have not been fully considered. Between 1986 and 1995 the Norwegian Medicines Control Authority received reports on adverse reactions related to topical use of beta-blockers in 17 patients. Six of these patients had cardiovascular and four of them severe respiratory symptoms. The latter group also included three fatal cases. The adverse effects seem to occur most frequently in the elderly, and it has been suggested that timolol should not be used in elderly people. Adverse effects related to treatment with topical beta-blockers are probably underreported in Norway.

Corneal astigmatism. The effect of transverse corneal incisions.

The results of transverse or combined transverse and radial keratotomy in eyes with idiopathic corneal astigmatism (N = 11), astigmatism+myopia (N = 9) or early stages of keratoconus (N = 6) are presented. The corneal astigmatism was reduced in all our patients, the absolute reduction being significantly correlated to the degree of preoperative astigmatism (p = 0.007). In the whole study group the mean relative reduction of the corneal astigmatism was 52.7%. In eyes without keratoconus the astigmatism recorded at the last follow-up visit was very similar to that measured a few days after surgery, while greater changes occurred in the keratoconus group.

Retrobulbar anesthesia with and without adrenaline in extracapsular cataract surgery. A prospective, randomized, double-blind study.

Seventy-five patients with senile cataract underwent a planned extracapsular cataract extraction. They were randomly divided into two groups, receiving retrobulbar anesthesia (4 ml lidocaine 2% and 250 IU hyaluronidase) with or without adrenaline. Patients in the adrenaline group had the lowest mean intraocular pressure after the retrobulbar injection (p < 0.02) and they required a shorter time of digital bulbar massage to reduce tension before surgery (p < 0.01). They also appeared to have a deeper anterior chamber during the first part of surgery, although the difference was not statistically significant. The duration of postoperative analgesia was significantly prolonged in patients receiving adrenaline. Different mechanisms explaining the effects of adrenaline in retrobulbar anesthesia are discussed.

Do we operate too many cataracts? The referred cataract patients' own appraisal of their need for surgery.

A questionnaire was sent to 379 patients referred for cataract extraction, asking them to assess their visual disability and their need for surgery. Two hundred and seventy-nine patients (73.6%) answered the questionnaire, this group being representative for the 379 patients regarding all relevant variables. The patient's answers were analyzed in relation to data extracted from their referral notes (visual acuity, monocular pseudophakia, age, sex, place of residence, referring ophthalmologist). The overall level of self-reported visual problems and need for cataract surgery were significantly correlated to a reduced best-eye visual acuity, although the correlation factor was low. A similar correlation between the subjective need for surgery and a worst-eye visual acuity < or = 6/24 was also found. Forty-seven patients (16.9%) answered that cataract surgery was not needed for the time being, and this attitude was not significantly correlated to the visual acuity, provided the acuity was > or = 6/24 in the best eye and > or = 6/36 in the worst eye. One hundred and twenty patients (43.0%) felt that their visual disability was so severe that they had to be operated within 1 month and 67 patients (24.0%) within 3 months, while 45 patients (16.1%) felt that surgery could be postponed for at least 6 months. Age, sex, place of residence and the presence of monocular pseudophakia were not found to significantly influence the level of self-reported visual problems. Only 18.3% preferred to be treated as out-patients.

The refractive error after implantation of a posterior chamber intraocular lens. The accuracy of IOL power calculation in a hospital practice.

The study included 188 patients, in which a posterior chamber intraocular lens was implanted after extracapsular cataract extraction. After modifications of the intraocular lens constants (SRK formula and SRK II formula) and correction of the axial length measurements (Colenbrander-Hoffer formula) had been made, the mean differences between the actual postoperative spherical equivalent and that predicted by the three formulas were -0.23D, -0.22D and -0.46D, respectively. More than +/-1.0D deviation from the predicted postoperative refraction occurred in about one-third of the cases. Inter-observed discrepancy regarding the accuracy of the preoperative measurement of the ocular axis length is suggested to be the main cause of unpredicted postoperative refractive errors.

Transverse keratotomy in postkeratoplasty astigmatism.

Transverse relaxing incisions were made in 12 eyes with a mean corneal astigmatism of 10.7D following penetrating keratoplasty. A few days later the mean graft astigmatism had been reduced to 5.5D (p = 0.0022), the reduction being significantly correlated to the degree of astigmatism before the keratotomy was done (p = 0.0044). Thereafter the corneal contour remained fairly stable through a mean follow-up period of 28.1 months, although a tendency towards a further reduction of the astigmatism was indicated. The mean corrected visual acuity improved from 0.5 before the keratotomy to 0.7 at the last control visit (p = 0.0117).

Suture adjustment in penetrating keratoplasty.

Postoperative adjustment of a single running penetrating corneal graft suture was done in 19 patients (22 adjustments). The short-term effect of this procedure was a mean reduction of corneal astigmatism of 4.39D (p < 0.0001). Thereafter, the corneal contour was fairly stable, provided that the running suture remained intact and tight. Localized loosening of the graft suture significantly increased the corneal astigmatism. Following removal of the graft suture no statistically significant mean change of corneal astigmatism was found. However, patients with a previously intact running suture tended to show increased astigmatism, while those with a previous localized suture loosening usually showed a decreased astigmatism after suture removal. The main benefit of suture adjustment is apparently the rapid and fairly stable reduction of postkeratoplasty astigmatism usually obtained, but unfortunately this effect seems chiefly to exist only as long as the graft suture remains intact and tight.

Retrobulbar anesthesia with and without hyaluronidase in extracapsular cataract surgery. A prospective, randomized, double-blind study.

Eighty patients with senile cataract were subjected to a planned extracapsular cataract extraction (ECCE) with implantation of a posterior chamber intraocular lens. Retrobulbar anesthesia was administered by injection of 4 mg lidocaine 2% with adrenalin. In 40 patients 150 I.U. hyaluronidase (Kinetin) was added to the anesthesia. The hyaluronidase group had a significantly lower frequency of iris prolapse, and deeper anterior chamber, both before and after expression of the lens nucleus. Possible mechanisms explaining the beneficial effect of hyaluronidase in extracapsular cataract surgery are discussed.

Epikeratophakia for keratoconus in mentally retarded patients. The use of fresh, free-hand made lamellar grafts.

Epikeratophakia for keratoconus was done in 11 mentally retarded patients, using fresh, free-hand made lamellar grafts. The mean follow-up period was 31.5 months. The grafts remained clear and well adapted in 7 cases (63.6%). Necrosis of the lower part of the graft occurred in 3 eyes (27.3%), and was probably caused by persisting epithelial defects. Only one of these grafts had to be removed. Despite concurrent eye diseases, such as cataract and possible amblyopia, an improved overall visual function was reported in 5 of the 11 patients (45.5%). No vision-threatening complications related to the epikeratophakia surgery was found.

Trabeculectomy and gelatin implants. A retrospective, long-term follow-up study.

In a retrospective follow-up study including 60 eyes with simple or capsular glaucoma, the results obtained by using a gelatin implant under the scleral flap during trabeculectomy were compared with those obtained without such implants. One month postoperatively the mean IOP was significantly lower in the gelatin group than in the control group (15.0 mmHg and 17.9 mmHg, respectively) (p = 0.024). At the long-term follow-up, however, the mean IOP in the two groups were very similar (13.6 mmHg and 14.8 mmHg, respectively).

Epikeratophakia for keratoconus. Long-term results using fresh, free-hand made lamellar grafts.

Epikeratophakia using fresh, free-hand made corneal grafts was done in 16 patients with keratoconus. The follow-up period averaged 27.8 months (range 13-45 months). A significant improvement of visual acuity was obtained (p = 0.002), and 14 of the 16 eyes (87.5%) achieved a corrected visual acuity greater than or equal to 6/12. The spherical equivalent and the cylindrical refractive error were reduced (p less than 0.05), and a significant flattening of the central corneal curvature was obtained (p less than 0.002). The mean postoperative central corneal astigmatism was 4.25 D. Postoperatively, the mean central corneal thickness was 0.670 mm, and the mean central thickness of the epithelialized graft was 0.336 mm. Six patients reported some postoperative glare or blurring of vision, despite a visual acuity greater than or equal to 6/9 on the Snellen chart. No significant subjective or objective changes were noticed after the 6-month postoperative follow-up visit.

The central corneal thickness in keratoconjunctivitis sicca.

The central corneal thickness of 17 patients with keratoconjunctivitis sicca was compared with the thickness recorded in a control group of 105 subjects with healthy eyes. A moderate, but highly statistically significant central corneal thinning was found in the keratoconjunctivitis sicca group. The possible etiology and clinical importance of this finding is briefly discussed.

Multiple-dose, dose-response relationship for the topical carbonic anhydrase inhibitor MK-927.

The multiple-dose, dose-response curve of MK-927 was studied in a five-center, double-masked, randomized, placebo-controlled, parallel study of 2%, 1%, and 0.5% MK-927 in 76 patients with bilateral primary open angle glaucoma or ocular hypertension and intraocular pressure greater than 24 mm Hg following washout of ocular hypotensive medications. Patients received doses at 8 AM and 8 PM for 14 days, and parallel 12-hour intraocular pressure curves were performed prestudy and on day 14, with 4-hour curves on days 1 and 4. There was a significant dose-response relationship, with 0.5% MK-927 twice daily being a minimal-effect dose. Both 1% and 2% MK-927 were active through 12 hours postdose, and peak mean percent decrease in pressure at 2 hours postdose was 18.6% and 20.6%, respectively.