Probleme bei der augen�rztlichen Bescheinigung von Blindheit

BACKGROUND

We compared the medical test results of 117 persons examined by the superintendent for blindness assessment in 2002 with their certificates of blindness (5.5% of the applications, 42% of the testimonial examinations performed in Hessen in 2002).

METHODS

If the ratings as "blind" or "severely visually handicapped" (corresponding to a visual acuity of not more than 0.02 or 0.05, resp.) differed between the medical test and the certificate, visual acuity, visual field, further findings, and the methods of assessment were analyzed on the basis of the medical records.

RESULTS

The medical test confirmed 75 certificates. Fourteen persons with a certificate of blindness were graded as severely visually handicapped by the medical test. In 8 and 12 cases, respectively, the criteria of neither blindness nor severe visual handicap were fulfilled. Eight persons with a certificate of severe visual handicap were graded as blind by the medical test.

DISCUSSION

In 29% of the cases, the visual handicap did not reach the certified grade. Striking differences occurred between the certificate and the functions shown in the medical test. In the certificates, the declared visual handicap was regularly judged to correspond to the objective findings, but apparently in these cases symptom validity had not been critically assessed. An improvement of diagnostic validity could be achieved using relatively uncomplicated subjective and objective tests.

Dissoziierte Naheinstellungstrias mit akkommodativem Konvergenzexzess

We report on an 8-year-old boy whose near reflex could be elicited exclusively when the left eye was fixing (LF) but not when the right eye was fixing (RF). With RE +1.25/-1.25/169 degrees and LE +1.0/-0.75/24 degrees, the visual acuity was 1.0 OU at 5 m and RE 0.5, LE 1.0 at 0.3 m improving to 1.0 OU by a near addition of 3.0 D. Stereopsis was 100 degrees (Titmus test). The prism and cover test revealed an esophoria of 4 degrees at 5 m. At 3 m there was an esophoria of 6 degrees (RF) and an esotropia of 28 degrees (LF), compensating to an esophoria of 3 degrees (RF/LF) with a near addition of 3.0 D. Accommodation and the pupillary near reaction (OU) were hardly elicitable during RF. During LF, retinoscopy revealed an accommodation of 8 D (OU) and the pupils constricted normally. Correction by bifocal glasses yielded orthotropia with random dot stereopsis at near.

Kestenbaum and artificial divergence surgery for abnormal head turn secondary to nystagmus. Specific and nonspecific effects of artificial divergence

Recommendations concerning the kind and dosage of eye muscle surgery for nystagmus vary in the literature. The present paper is an evaluation of the effects of Kestenbaum and artificial divergence surgery on abnormal head posture in a retrospective study. Exclusively patients with surgery for nystagmus-related horizontal head-turn (HT), with binocular vision and without previous eye muscle surgery were considered. Of the 78 patients, aged 3 to 68 years, 52 had a HT to the left side; 47 patients were male. In the Kestenbaum group (n = 31), the preoperative HT of 30 degrees (20-40) (median, 0.1-0.9 quantile) was reduced to 10 degrees (0-30) by surgery of 14 mm (10-20) on each eye. Four patients received further surgery. In the artificial divergence group (n = 27), the HT of 30 degrees (25-40) was reduced to 5 degrees (0-20) by recess-resect surgery of 10 mm (7-12) on the adducted eye. Seven patients needed further surgery. In the combined Kestenbaum plus artificial divergence group (n = 20), the HT of 30 degrees (25-40) was reduced to 7 degrees (-5-15) by surgery of 29 mm (21-37) on both eyes together. No further surgery was necessary. Kestenbaum surgery had a similar effect/dose ratio as recess-resect surgery for strabismus. If a test with base-out prisms suggests that artificial divergence is promising, this concept is preferable. It can be integrated into Kestenbaum surgery.

[Dissociated horizontal deviations (DHD): nomenclature and etiology. An orientating attempt in terminological confusion]

PURPOSE

To classify dissociated horizontal deviations (DHD) based on the etiology of the vergence that causes the dissociation of the squint angle.

METHODS

Dissociated strabismus can reliably be diagnosed by a change of the squint angle caused by an alternation in the fixation from one eye to the other, when all the other conditions (head posture, direction of gaze, fixation distance, accommodation) remain unchanged. The decisive diagnostic tool is the reversed fixation test: During monocular fixation with one eye, the squint angle of the other eye is neutralized using a synoptometer or a prism. Then, the fixation is changed to the other eye, which keeps its position behind the prism. If the change in fixation causes a change in the position of the previously fixating eye, the deviation is dissociated. If the position of the previously fixating eye does not change, the deviation is not dissociated.

RESULTS

Dissociated strabismus can be detected and differentiated from both comitant and incomitant non dissociated strabismus by the reversed fixation test. The dark red glass test is less sensitive and less specific for dissociated strabismus than the reversed fixation test, if a difference in accommodative convergence is excluded, possible causes of DHD are nystagmus-attenuating convergence, substitution of version eye movement by convergence, and a horizontal side effect of the vertical eye muscles in asymmetric DVD.

CONCLUSION

Dissociated strabismus is an effect of vergence which is brought about by the change in the fixation or dominance from one eye to the other eye or in the interocular ratio of afferent input (luminance). Dissociated strabismus can be classified based on its direction or due to its etiology.

[The closed Landolt ring--a handy test for evaluating suspected simulation]

PURPOSE

We present a visual acuity test for proof of malingering and psychogenic impairment of visual acuity.

METHOD

The book contains 36 plates. On 32 plates, a Landolt-C is shown with a gap of 10 minutes of arc, thus corresponding to a visual acuity of 0.1, when applied at a distance of 1 metre. Each of the 4 alternatives of the Landolt-C occurs eight times in random order. Starting at position 21, four plates are interspersed showing a closed circle of the same size. The test is used at a distance corresponding to an acuity level of maximum 50% of the presumed factual acuity. Following a four alternative forced choice paradigm, the tested person is requested to call the direction of the Landolt-C within about 2 seconds, when the plates of the book are turned over. The responses and their latency are recorded using a digital electronic system which allows later audiovisual analysis. The response on the first closed circle and its latency is compared to the previous responses. Two subjects were tested who tried to pretend a reduction of their visual acuity.

RESULTS

Malingering was proved by the verbal response of the first subject and by the long latency of the response of the second subject (4.0 s vs. 1.2 s-2.7 s for the previous responses). The entire test, explanation included, took less than 5 minutes.

CONCLUSION

This handy test can be a useful tool in cases suspect of malingering or psychogenic impairment of visual acuity.

Surgery for nystagmus related head turn: Kestenbaum procedure and artificial divergence

PURPOSE

An abnormal head posture adopted to reduce a nystagmus can be treated by Kestenbaum surgery or by creating an exodeviation which is compensated by convergence (artificial divergence). We evaluated the effects of Kestenbaum surgery and artificial divergence surgery in a retrospective study.

METHODS

Seventy-eight patients who received surgery for horizontal head turn (HT) due to nystagmus were included in the study. Exclusion criteria were previous extraocular muscle surgery, strabismus, lack of binocular vision, and cerebral disease. The millimetres of surgery and the findings before and 3 months after operation [HT, binocular visual acuity (VA), binocular vision (BV)] were evaluated. The patients were divided into three groups: the Kestenbaum group, the artificial divergence group, and the artificial divergence plus Kestenbaum group.

RESULTS

Of the 78 patients, aged 3-68 years, 52 had HT to the left side and 47 were male. In the Kestenbaum group (n=31), the median (10% and 90% quantile) HT was 30 degrees (range 20-40 degrees). A total of 28 mm (range 20-40 mm) surgery reduced the HT to 10 degrees (0-30 degrees). The efficacy of surgery was 1.4 degrees HT reduction per millimetre surgery on one eye (range 0.4-2.5 degrees). Four patients received further surgery. In the artificial divergence group (n=27), 10 mm (range 7-12 mm) surgery reduced the HT of 30 degrees (range 25-40 degrees) to 5 degrees (range 0-20 degrees). Seven patients received further surgery. In the artificial divergence plus Kestenbaum group (n=20), the HT was 30 degrees (range 25-40 degrees). A total of 29 mm (range 21-37 mm) surgery reduced the HT to 7 degrees (range -5 degrees to 15 degrees). No further surgery was performed. Postoperatively, the maximum VA and BV was available without large HT, but an increase in the absolute VA and BV could not be proved.

CONCLUSION

Artificial divergence is preferable or should be combined with Kestenbaum surgery, if possible. Kestenbaum surgery alone has an effect/dose ratio similar to recess-resect surgery for strabismus. Thus, to correct x degrees HT, 2/3x mm surgery on each eye is adequate.

[Unilateral aplasia of a lateral rectus muscle]

BACKGROUND

The congenital absence of an extraocular muscle is rare. The case of an unilateral lateral rectus muscle and a review of the literature are presented.

PATIENT AND METHODS

A healthy 7-year old boy with inconspicuous family history was seen in our clinic. The boy had been noted to have a right esotropia from infancy. Clinical orthoptical examinations and magnetic resonance imaging (MRI) were performed. The esotropia was corrected by transposition of the superior and inferior rectus muscle.

RESULTS

With correction of the myopic astigmatism the visual acuity of either eye was 0.8. The right eye could not abduct to pass the midline, the left eye passed the midline by 35 degrees. From the primary position the right eye was able to elevate by 20 degrees and the left eye to elevate 15 degrees. The alternate prism and cover test showed in either eye fixation an esotropia of 24 degrees without significant change in elevation or depression. Besides, there was a hypertropia (+VD) of 14 degrees which increased to 21 degrees in left gaze and decreased to 0 degree in right gaze. Indirect ophthalmoscopy showed a bilateral excyclo position of approximately 5-10 degrees. Retraction of either eye was not seen in any gaze direction. The axial length of the right/left eye was 25.2 mm/24.6 mm. Aplasia of the right lateral rectus muscle and hypoplasia of the left lateral rectus muscle could be demonstrated by magnetic resonance imaging. Intraoperatively the right lateral rectus muscle was absent. The vertical eye muscle inserted regularly. Hummelsheim's procedure was performed. Eight months postoperatively, the boy was orthotropic in primary position. The inferior oblique overaction was still present together with a "V" pattern of 8 degrees. The Bagolini test was positive.

CONCLUSION

The congenital absence of one or more extraocular muscles is a rare condition, which has to be considered as a differential diagnosis to neurogenic nerve palsy.

[Results of combined divergence operation in intermittent exotropia in 120 children]

BACKGROUND

Intermittent exotropia is the most frequent indication for surgical correction of exodeviations in childhood. Overcorrection with prolongated or persistent consecutive esotropia can impair binocular vision particularly in early childhood. We wanted to investigate this potential risk and the dose/effect relation of recess-resect surgery on children.

PATIENTS AND METHODS

120 children up to ten years of age underwent recess-resect surgery for intermittent exotropia in our clinic from 1991 to 1999 (< 2% of the surgical cases). The cycloplegic refraction was spectacle corrected with a reduction of 0.5 dpt. Preoperatively, a diagnostic occlusion was performed for three days. The amount of surgery was calculated using our dosage schedules based on effects one week postoperatively. The squint angles as measured by the alternate prism and cover test at 5 m and 0.3 m pre- and 3 months postoperatively and the binocular functions as measured by the Bagolini striated glasses, Titmus, Randot, TNO, or Lang tests were evaluated.

RESULTS

(Medians) Squint angles in primary position were: preoperative: distance (5 m)--15 degrees, near (0.3 m)--16 degrees; postoperative (n = 104); distance--4 degrees, near--3 degrees. Effectivity of surgery: distance: 1.3 degrees/mm, near 1.4 degrees/mm. Consecutive esotropia requiring surgical correction occurred in 1 child. Second surgery for intermittent exotropia in the years 1991 to 1999 was necessary in 5 children. Binocular functions (n = 95): Preoperative = postoperative: 61%, postoperative > preoperative 21%, postoperative < preoperative 18%. The diagnostic occlusion was helpful to differentiate "pseudo-divergence excess type" from "divergence excess type" exotropia. The average deviation did not increase under the diagnostic occlusion. The effectivity of surgery (degree/mm) in the children group was lower than in a compared group of older patients (> 10 years) with intermittent exotropia.

CONCLUSION

Using our own dosage schedules and surgical technique, residual exodeviations are common after recess-resect surgery in childhood. The risk of consecutive esotropia or persistent impairment of binocular vision is low.

[Congenital nystagmus: indication, results and dosage of Kestenbaum surgery in 34 patients]

BACKGROUND

Abnormal, nystagmus related head postures can be treated by Kestenbaum's procedure, if the concept of artificial divergence (Cüppers procedure) is not expected to work. In this retrospective study, we evaluated the effects of Kestenbaum surgery in order to establish dosage recommendations.

PATIENTS AND METHODS

Solely patients who received Kestenbaum surgery (maximum 3 mm dosage difference between both eyes, i.e., without additional artificial divergence) for a horizontal head turn (HT) due to nystagmus were included in this study. Exclusion criteria were previous eye muscle surgery, strabismus, lacking binocular vision, and cerebral disease. The millimetres of surgery and the pre- and 3-6 months-postoperative findings (HT and visual acuity at 5 m distance, stereopsis) were evaluated.

RESULTS

Of the 34 patients, 21 had a HT to the left side and 20 were male. The age at surgery (median, 10%- and 90%-quantile) was 7 years (4-32), the total amount of surgery 32 mm (20-40), and the preoperative HT 30 degrees (20-40). Postoperatively (n = 31), the HT amounted to 7 degrees (0-20). The reduction of HT was 67% (25-100), the efficacy of surgery 0.8 degree (0.3-1.0) per millimetre total amount of surgery on both eyes together. Four patients needed further surgery due to residual HT. Postoperatively, the maximum visual acuity was available without HT or with significantly less HT than preoperatively. Stereopsis showed a trend of improvement.

CONCLUSIONS

The Kestenbaum procedure has a dose/effect ratio similar to that of recess/resect surgery for strabismus. Due to a long term efficacy of 1.5 degrees/mm, a dosage (in millimetres) on each eye of two thirds of the HT (in degrees) can be recommended. Physiological and methodical factors (false measurements) have to be discussed as an explanation for apparently low efficacy of surgery.

[Pathophysiology, diagnosis and therapy of three congenital dacryocystoceles]

BACKGROUND

Congenital dacryocystocele has been rarely described in German literature. Congenital obstruction and distention of the lacrimal sac makes it necessary to differentiate for various causes.

PATIENTS AND METHODS

Three infants had congenital dacryocystocele. The diagnosis was made by sonography and was established by probing the lacrimal duct and nasal endoscopy that showed a white prominent tumor below the lowest conch.

RESULTS

Directly after endonasal and canalicular opening of the dacryocystocele clear liquid with white detritus drained, and the swelling decreased. No further procedure was needed.

CONCLUSION

The diagnosis of dacryocystocele can be made by inspection, probing the lacrimal duct, ultrasound and nasal endoscopy. If probing of the lacrimal duct could not easily open the Hasner's membrane, endonasal opening can be performed. The cooperation with an ear-nose-throat specialist could lead to the diagnosis of dacryocystocele and sufficient treatment without the need for any further radiological examinations.

Reduction of postoperative nausea and vomiting by dimenhydrinate suppositories after strabismus surgery in children

Although dimenhydrinate has been used for treatment and prevention of postoperative nausea and vomiting (PONV) since the fifties, there have been few controlled studies about its efficacy. We performed a double-blinded study of 301 children aged 4 to 10 yr who underwent strabismus surgery. Preanesthetic medication with midazolam (0.5 mg/kg) as well as application of either dimenhydrinate suppositories or a placebo preparation was performed 30 min before the induction of anesthesia. Anesthesia was induced with thiopentone (5-10 mg/kg) and vecuronium (0.1 mg/kg) and maintained with halothane (1%-2%) in N(2)O/O(2) (65%/35%). The incidence of PONV, requirements for rescue dimenhydrinate, and time to recovery were recorded. The overall incidence of PONV was 60.1% in the placebo group and 30.7% in the dimenhydrinate group. In the dimenhydrinate group, children had to be observed in the recovery room significantly longer than those in the placebo group. Children having received dimenhydrinate were discharged from the recovery room with lower arousal scores. We conclude that the rectal administration of dimenhydrinate is effective for the prevention of PONV, although the sedative effect may require longer postoperative monitoring.

IMPLICATIONS

We performed a double-blinded, randomized study to investigate the effects of prophylactic rectal dimenhydrinate application on postoperative nausea and vomiting in children undergoing strabismus surgery. In comparison with placebo, dimenhydrinate reduced the incidence of postoperative vomiting from 60.1% to 30.7%.

[Healing process and complications after eye muscle surgery]

BACKGROUND

Varying reports on the incidence of operative and postoperative complications following eye muscle surgery have been published. The purpose of this study was to quantify complications after various types of eye muscle surgery as well as minor pathological changes of the anterior and posterior segment.

PATIENTS AND METHODS

This prospective study included all patients who underwent eye muscle surgery at the Department of Strabismology and Neuroophthalmology, Giessen, from January to May 1998. Five hundred eyes of 377 patients aged 2-82 years were included. The spectrum of procedures comprised: recessions, resections, tucks, R&R procedures, transpositions, bimedial retroequatorial myopexies, and revisions of rectus and oblique muscles. All patients were examined 1 day preoperatively and 1 day, 1 week, and 3 months postoperatively. Any complications and even minor pathological changes of the anterior and posterior segment were documented. Some changes were assessed by means of a score (0-3).

RESULTS

One day postoperatively, 30% of eyes had inflammatory pseudoptosis, most of them mild. Conjunctival swelling and injection were frequently mild and moderate, after 1 week mostly mild. Conjunctival irritation was more pronounced following resection than tucking. Punctate epithelial keratopathy was noted in 1.6% of cases (first postoperative day), dellen in 4.3% (first postoperative week). Three months postoperatively, 14.3% of eyes had biomicroscopically visible conjunctival folds and 91.3% had minimal conjunctival scars. None of the patients had a scleral perforation or other serious complication.

CONCLUSIONS

Eye muscle surgery rarely entails complications. Revisions due to organic pathological changes are extremely rare. Possible development of dellen requires check-up 4-7 days postoperatively. Tucking of rectus muscles causes less conjunctival irritation than resection.

[Vertical vergence in convergence]

PURPOSE

To report on a 7-year-old boy with a small left-over-right deviation (-VD) which increased when the head was tilted to the left shoulder and during convergence.

METHODS

The squint angles were measured by the unilateral and alternate prism cover test at distance and near fixation when the head was in ortho-position and when it was tilted.

RESULTS

At distance fixation (D) there was a latent deviation of-VD 3 degrees. With near fixation (N) at 0.3 m the vertical phoria increased to-VD 18 degrees. The angle of deviation was not influenced by (N) convex lenses in front of the fixating eye despite an adequate dis-accommodation. The-VD was fairly comittant in right and left gaze. At 45 degrees head tilt to the right shoulder the-VD decreased to (D) 2 degrees and (N) 12 degrees. At 45 degrees head tilt to the left shoulder the-VD increased to (D) 18 degrees and (N) 26 degrees. A dissociated vertical deviation was excluded by the dark red glass test and by the reversed fixation test.

CONCLUSION

The disturbance can be explained by a, presumably congenital, supranuclear misinnervation and has to be differentiated from other types of vertical deviation.

[Determining visual acuity with LH symbols and Landolt rings]

PURPOSE

Lea (LH) symbols seem to be favourable for visual acuity assessment in childhood. The symbols of the LH test are well standardized and applicable to preschool children. We compared the visual acuity determined by LH single symbols (LH) and the acuity measured with the Landolt-C (LC).

PATIENTS AND METHODS

138 cooperative subjects aged 7 to 91 years were examined. Their visual acuity was either normal or reduced due to various etiologies. Their refractive error was corrected. The monocular LH and LC were determined by a 3/4 criterion (study 1). In 19 healthy subjects aged 21 to 58 years, acuity was reduced stepwise by 5 different calibrated occlusives (study 2). A Lighthouse single symbol book (LH symbols) was used at a distance of 3 m. LC was determined at a distance of 5 m. The luminance of the test field was 180-200 cd/m2. The right eye of each patient and the amblyopic eye of the squinting patients was taken for statistical evaluation. The strabismic patients' interocular differences of LC and LH were compared.

RESULTS

Within study 1, LC ranged from 0.02 to 2.0 and LH from 0.03 to 2.5. LH overestimated LC by 1.4 lines on an average (t-test p < 0.0001). The regression equation lgLH = 0.95 lgLC + 0.11 describes a high correlation (r = 0.95) between LH and LC. The relations between LH and LC of 43 strabismic amblyopic patients and the remaining subjects did not significantly differ. Due to the criterion of an interocular LH-difference > 1 line, 85.7% resp. 90% of the strabismic amblyopic patients with an interocular LC difference > 1 resp > 2 lines were detected. In study 2, LC ranged from 0.1 to 1.6, LH from 0.12 to 2.0. The mean difference LH-LC was 1.3 lines. The regression equation was lgLH = 0.91 lgLC + 0.08 (r = 0.95).

CONCLUSION

LH symbols allow a reliable measurement of recognition acuity. Due to the design of the symbols, they are excellently suitable for application to preschool children. Age related normal values should be established. The systematic difference between the LC acuity and the LH acuity measured with the Lighthouse LH single symbol book by 1.4 lines has to be considered.

[Causes of blindness in Hessia in 1996]

BACKGROUND

Despite of medical progress, the incidence and prevalence of blindness are continuously increasing. In Hessia, the number of persons receiving blindness compensation payment increased from 8,346 in 1985 to 11,166 in 1996 by 2.6% per year. In 1996, the rate (prevalence) amounted to 1.85/1000 of the Hessian population.

METHODS

In this study, the incidence of blindness (visual acuity < or = 0.02 or equivalent visual handicap) and substantial visual handicap (visual acuity < or = 0.05 or equivalent visual handicap) according to the Hessian law was investigated by means of the records of new candidates for blindness compensation payment whose applications were granted in 1996. The causes of blindness (main diagnosis), visual acuity, age, gender, and nationality were evaluated.

RESULTS

The Hessian administration for public welfare had filed 2,609 alterations of applications concerning sundry social assistance. Out of these, 2,395 files (91.8%) were available, 1411 applications met the requirements for blindness compensation payment, 45.4% were graded substantially visually handicapped for the first time, 43.4% were graded blind for the first time, and 11.0% were graded blind after previous substantial visual handicap. In 0.2%, a further classification was not necessary. Applied to the Hessian population of 6.027 million people, the incidence of blindness was 0.14/1000. 67.9% were female, 30.9% were male, in 1.2% the gender was not evaluable. The age median of the candidates was 78 years (male: 74 years, female: 80 years), 84.3% of the candidates were > or = 60 years old. The most frequent causes of blindness (substantial visual handicap) were: age related macular degeneration 35.3% (49.5%), diabetic retinopathy 15.0% (17.0%), glaucoma 12.6% (7.8%), tapetoretinal degenerations 6.9% (1.7%), optic nerve atrophy 6.1% (4.3%), and myopia 5.0% (6.5%).

CONCLUSION

Age related affections are the most frequent causes of blindness. Due to the increasing life expectancy and rather constant birth rates, a further increase of blindness rates has to be expected.

[Clinical application of a new method for the objective estimation of minimum visual acuity]

PURPOSE

Recently, a new method for the objective estimation of the minimum visual acuity (OEM) by means of suppression of the optokinetic nystagmus has been presented (Klin Monatsbl Augenheilkd 1998;212:196-202). This study reports on the clinical use of this method.

METHODS

In 120 individuals referred to our clinic either to procure an ophthalmological expert opinion or for differential diagnosis of an unclear visual impairment, an OEM was performed. The result of the OEM was compared to the clinical findings (history, biomicroscopy of anterior and posterior segments, objective refractometry, pupillary responses, binocular alignment, motility, binocular vision, colour vision, applanation tonometry, electrophysiology, fluorescein angiography, neurologic, radiologic, psychiatric findings, reproducibility of visual acuity and visual field statements under different conditions, comparison of subjective and objective visual field data, statistical prove of false visual acuity and visual field statements) which were critically interpreted concerning the credibility of the subject's statements.

RESULTS

As a result of the clinical examinations, the stated visual acuity of 62 individuals was credible. In one of these individuals, the OEM pointed to a slightly (1dB) better visual acuity. The statements of 7 individuals could not be categorized clinically. The OEM pointed to a better acuity in 3 cases. The stated vision of the remaining 51 individuals was not credible. In 38 of these cases, the OEM pointed to a better acuity, or false statements could be proven by the OEM.

CONCLUSION

A significant rate (75%) of the individuals whose statements were not credible was detected by the computer-aided, nystagmographic method of OEM. The method allows an estimation of the actual minimum visual acuity and yields evidence of false statements concerning the detection acuity.

Sensitivity of the MTI photoscreener for amblyogenic factors in infancy and early childhood

BACKGROUND

Screening for amblyogenic factors in infancy by pediatricians is unsatisfactory, as they hardly ever detect ametropia or microstrabismus. As photoscreening seems to be a helpful method to detect even small squint angles and refractive errors, we tested the MTI photoscreener for its sensitivity with respect to amblyogenic factors.

PATIENTS AND METHODS

One hundred and twelve children aged 6-48 months were first examined with the MTI photoscreener. Then each child underwent complete medical examination by an ophthalmologist and an orthoptist. The examination included the Hirschberg test (corneal reflex evaluation), the Brückner test (fundus red reflex), and, where possible, the Lang stereotest, the cover test and visual acuity assessment, as well as a motility test, biomicroscopy, ophthalmoscopy in mydriasis and refractometry in cycloplegia. Exclusion criteria were any organic pathological results, manifest strabismus, ametropia > or = 2 D and astigmatism > or = 1 D. An orthoptist, a pediatrician and two ophthalmologists independently evaluated the Polaroid pictures according to the criteria given in the handbook of the MTI photoscreener.

RESULTS

For 10 children the evaluation with the MTI photoscreener was not possible despite the fact that photographs were retaken several times. Thirteen photographs showing obvious pathologic findings despite their poor quality were included. Eighty-three of the remaining 102 children failed the eye examination according to the above-mentioned criteria. The mean sensitivity of the MTI photoscreener was determined to be 82.8%. The ability to correctly identify the absence of any amblyogenic factors (specificity) was 61.8%.

CONCLUSIONS

Sensitivity was high when compared to the usually low detection rate during pediatric examinations. Due to the low specificity, effectiveness was poor. Therefore an ophthalmological examination should be included in the preventive screening during infancy and early childhood.

[Objective assessment of minimum visual acuity by suppression of optokinetic nystagmus]

PURPOSE

To develop and to validate an objective method which allows an estimation of the visual acuity (VA) of adults.

METHODS

A horizontal optokinetic nystagmus (OKN) was elicited by a vertical rectangular grating presented on a PC-screen and was recorded by an infrared reflection method. Superimposition of three stationary black detection stimuli was used to suppress the OKN. The size of these stimuli was increased every two seconds, in ten steps. Suppression of the OKN was taken as an indication that the stimuli were detected. The relation between the smallest effective stimulus and logVA was evaluated in 65 healthy volunteers (130 eyes) with artificially reduced VA and 425 cooperative patients (842 eyes) whose VA was reduced due to different etiologies. The tolerance intervals of logVA related to the discrete detection stimuli were calculated.

RESULTS

The method allows an estimation of the least expectable VA in steps of 0.8, 0.32, 0.25, 0.12, 0.1, 0.06, 0.03 und 0.025 due to the smallest value of three trials. The least VA of strabismic amblyopic eyes can only be estimated in steps of 0.16, 0.06, and 0.02. A VA > 0.02 can be proven with high reliability.

CONCLUSION

The method allows a clinically useful, objective estimation of the least VA without observer bias in non-amblyopic eyes.

[Visual field examination in limited patient cooperation]

Objective methods to estimate the visual field are necessary, if a conventional subjective perimetry is impossible due to limited cooperation. Objective methods are indicated in infants, handicapped patients, patients with psychogenic visual field loss, and malingerers. An objective estimation of the visual field can be performed by means of pupillary light reflexes, voluntary and involuntary eye movements, and visual evoked potentials. Systematically false responses contain useful information regarding the proof of misrepresentations. The reproducibility of visual field defects can be checked by testing at different distances from the screen. This article reports on handy methods requiring no large-scale equipment.

[Examinations with the Cardiff Acuity Test]

Recently, a new preferential looking (PL) test has been presented for measuring visual acuity in infants and young children (Cardiff Acuity Test, CAT). The PL target is a schematic vanishing picture composed of isoluminant lines with different spatial orientations. Fifty-three healthy children (4-34 months, group 1), 28 (4-35 months) children at risk for amblyopia due to strabismus (group 2), 19 healthy subjects, and 157 patients (group 3) were tested with the CAT. In group 2 the CAT was compared with the fixation preference test. In group 3 the CAT was compared with a recognition test (Landolt C test). In group 1 the interocular difference of the CAT data was a maximum of 1 dB (70% 0 dB, 30% 1 dB, 1/3 so-called octave). Thus, an interocular difference of > 1 dB was considered to be suggestive of monocular or asymmetrical visual impairment. The maximum value 6/6 was frequently achieved (RE 44%, LE 36%, > 18 months RE 57%, LE 46%). In group 2 only 20% of the monolateral strabismic children showed an interocular difference > 1 dB in the CAT. In group 3 we found significant correlations between the CAT and Landolt acuity. A ratio of about 1.7/1 between CAT and Landolt acuity remained constant in cataract eyes as compared to healthy eyes. In amblyopic eyes due to strabismus this ratio was 3.7/1. Thus, amblyopia was underestimated with the CAT. Without limiting the examination distance, interocular differences > 1 dB in the CAT occurred in 52% of the strabismic amblyopic patients (potential sensitivity). At a distance of 1 m this rate decreased to 22% (real sensitivity). In conclusion, the CAT definitely lacks sensitivity for strabismic amblyopia. The data suggest that the real sensitivity could be improved by using higher spatial frequencies. The use of familiar shapes instead of gratings such as PL targets affects cooperation favorably in 12- to 36-month-old children.

[Bilateral congenital mydriasis with accommodation failure]

In the literature congenital mydriasis is described as a very rare condition and explained as a result of isolated aplasia of the iris sphincter muscle. Aplasia of the ciliary muscle was assumed to cause congenital accommodation insufficiency. A case of congenital mydriasis with lack of accommodation is presented. The first ophthalmological check-up was 2 weeks after surgery for a persistent ductus arteriosus Botalli. The girl was 15 weeks old. Her parents had watched her dilated pupils since birth. The diameter of both pupils was 6.5 mm. They did not react to light, lid closure, or conjunctival administration of pilocarpine solutions up to 1%. A refractive error of OD +3.0 D and OS +2.5 D was measured by retinoscopy. The hypermetropia was also uninfluenced by topical locarpine 1%. Two drops of pheylephrine 2.5% caused additional pupillary dilatation of 0.5 mm. Besides the lack of accommodation and pupillary constriction, all ocular findings were regular. No chromosomal abnormalities were found. No further cases of pupillary disorders are known in the family. These findings can only result from the lack of cholinergic sensitivity or aplasia of the pupillary sphincter and ciliary muscle. The infant was supplied with bifocals and sunglasses. The near correction was spontaneous. At the age of 15 months there was a grating acuity of 20/80, which is in the normal range, as measured by preferential looking.