Hirschberg Test Research Articles

The Angle Kappa in Strabismic Individuals

Purpose To determine angle kappa values in strabismic individuals by means of a synoptophore. Methods One hundred-and-eight strabismic subjects and 102 healthy subjects who served as a control group were enrolled in the study. A complete ophthalmologic examination, including determination of refractive status, best-corrected visual acuity measurement, slit-lamp biomicroscopic anterior segment evaluation, intraocular pressure measurements with a Goldmann applanation tonometer, and dilated fundus examination, was done on all study participants. Orthoptic examination included Krimsky prism reflex test, prism cover test, and duction tests. Strabismic patients were grouped into two categories according to their deviation types: exotropic and esotropic. A synoptophore (Clement Clarke, London, England) with a specially designed slide (Maddox test slide series A White Binding No: 16; Clement Clarke, London, England) was used to measure angle kappa. Results Of the 108 strabismic patients, 62 were males and 46 were females with a mean age of 23.38 ± 3.68 years (range: 8 to 82 years). There were 54 males and 48 females with a mean age of 32.74 ± 1.63 years (range: 7 to 68 years) in the control group. The exotropic group had significantly higher angle kappa values than either the controls or the esotropic group (independent sample t-test, p < 0.001). None of the study participants had negative angle kappa values. Higher average kappa values were obtained in left eyes than in right eyes in all three groups (student t-test, p < 0.01 for all groups). Conclusion This study showed that exotropic patients have higher angle kappa values when compared to esotropic patients. Ophthalmologists must take the kappa angle into account when performing a Hirschberg or Krimsky test in young and uncooperative patients in order to improve surgical results.

Intraoperative eye position after sub-Tenon's anesthesia for cataract surgery

Background: To evaluate the incidence and extent of ocular deviation associated with sub-Tenon's anesthesia. Methods: Seventy-five consecutive patients undergoing routine phacoemulsification with sub-Tenon's anesthesia at the Eye Unit, Royal Gwent Hospital, were prospectively enrolled in this observational case series. The exclusion criteria were patients taking warfarin, or patients with preexisting ocular motility disorders,allergy to local anesthetics,or previous surgery for squint or retinal detachment. Eleven patients were subsequently excluded from the study group as they required additional anesthesia blocks before measurements were taken for ocular deviation. We injected 5mL of a local anesthetic mixture of 2% lignocaine and 7.5 mg/mL levobupivacaine in the sub-Tenon's space in the inferonasal quadrant. Ocular deviation was assessed objectively by means of the Krimsky test. Forced duction tests were performed before and after anesthesia. Results: Hyperdeviation was documented in 49 (77%) eyes, exodeviation in 62 (97%), and hypodeviation in 6 (9.4%). No esodeviations were documented. Only 2 patients were orthophoric after anesthesia. Mean vertical deviation was 4.4 prism dioptres (PD) (SD 4.7 PD, 95% CI 3.2–5.5 PD, range 0–14 PD). Mean horizontal deviation was 19.5 (SD 9.6, 95% CI 17–22, range 0–50) PD. Forced duction test revealed no mechanical restriction before or after anesthesia. Interpretation: This study suggests that there is an appreciable ocular deviation with sub-Tenon's anesthesia. Intraoperative ocular deviation may make certain procedures more difficult; therefore, we recommend a low threshold for an additional corrective block administered before surgery to rectify the deviation.

Positive angle kappa in albinism

Background Albinism is an inherited disorder of deficient melanin production. There is a high prevalence of strabismus in patients with albinism. We investigated the prevalence of a positive angle kappa in patients with albinism and report its effect on assessment of binocular alignment. Methods We retrospectively reviewed the charts of 207 consecutive patients with the diagnosis of albinism seen at the University of Minnesota between 1984 and 2002. Angle kappa and alignment using prism and alternate-cover test (PACT) and Krimsky measurements were recorded. Results In 99.6% of our patients with albinism, angle kappa was noted to be positive. The mean difference between PACT and Krimsky measurements was 17.11 prism diopters in the more exotropic (or less esotropic) direction per Krimsky test. Because of the high prevalence of a positive angle kappa, esodeviations often appeared less and exodeviations appeared greater than when measured using PACT. Conclusions Positive angle kappa can be considered another clinical feature of albinism. Consideration should be given to the effect of positive angle kappa on alignment as observed by Krimsky measurement when planning extraocular muscle surgery, particularly when preoperative sensory testing suggests binocular potential.

Development of refractive error and strabismus in children with Down syndrome.

To investigate the development of refractive errors and strabismus in a cohort of children with Down syndrome. Data for 55 children with Down syndrome who are participating in this longitudinal study of visual development, first examined by us when aged less than 2 years and on at least two other occasions, were analyzed. Mohindra retinoscopy was used to measure refractive error. Ocular alignment was assessed using the Hirschberg test and, when possible, the cover test. Despite the high prevalence of large refractive errors in children with Down syndrome, longitudinal data showed that these are not always present in early infancy. Twenty-one (38%) of the children were emmetropic throughout the study. Of the 24 children with a significant refractive error at the outset, only 6 (25%) showed emmetropization. The others retained or increased their refractive errors. The remaining 10 children were emmetropic at the outset, but then had a significant refractive error develop. There is a high prevalence of strabismus in children with Down syndrome (29% of the total group), which cannot be attributed to the presence of hypermetropia or anisometropia. The retention or development of infantile refractive errors in many children with Down syndrome indicates a failure of emmetropization. All children were at risk of strabismus whatever the refractive error. The findings have implications for timing of screening programs.

Prevalence of common visual problems among primary school children in Calabar Municipality, Nigeria

A study to determine the prevalence, types and degree of severity of ametropia, hyperopia, myopia and astigmatism among 956 primary school children from 10 selected schools in Calabar, Nigeria was conducted. Pre-tested questionnaires were administered by two ophthalmic nurses. Penlight examination, Hirschberg's test, fundoscopy with a direct ophthalmoscope without and when necessary, with pupillary dilation were performed by one optometrist. All subjects whose visual acuity were less than 6/6 in any eye, all who have at one time in their lives been given corrective glasses for error of refraction were refracted. When all cases of ametropia were considered, a prevalence of 14.9% was found. Hypermetropia predominated (7.8%), followed by myopia (3.6%) and astigmatism (3.5%). Ninety percent of the children with vision less than 6/6 in any eye could have their vision improved by refractive complications and disability. A total of 62.4% of these children with visual disability could have their functional vision in class improved without glasses by being moved to the front row in class. KEYWORDS: Ametropia, Primary School Children, Calabar, Nigeria (Global J Med Sci: 2003 2(1): 23-26)

Preliminary report: Examination of young children with Lea symbols

Lea symbols are highly sensitive for detection of amblyopia in cooperative patients. They are favorable for visual acuity assessment in childhood. Therefore, we assessed age-related normal values and interocular differences of Lea symbol visual acuity. We reexamined 50 out of 193 children aged 21 months to 7 years who came for a routine pediatric examination between January and November 1999. Lea symbol acuity (Lea Symbols Single Symbol Book (LS) and Lea 15-Line Folding Distance Chart (CLS)) and Landolt-C acuity (single (LC) and crowded with 2.6' inter-optotype distance (LC(2.6))) were measured. A three out of four criterion was used. Strabismus and any organic eye disease were excluded by orthoptic and ophthalmologic examination, consisting of biomicroscopy, ophthalmoscopy, retinoscopy or refractometry, cover test or Hirschberg test and Lang Stereotest. Only 26% of the parents (50 out of 193) accepted an examination in our hospital. In 35 (32) of the 50 children, visual acuity could be measured in both eyes separately with single (crowded) Lea symbols, while 26 (25) children could be examined in both eyes monocularly with the Landolt-C with single (crowded) optotypes. Except for one 3-year-old boy, all of the children older than 30 months could be tested with single Lea symbols. Lea acuity surpassed Landolt acuity. The difference was about 1.5 lines (1.5 dB) for both the single and the crowded optotypes. In 63% (69%) of the children who could be tested monocularly, LS acuity (CLS acuity) was higher than 0.8 (0.63). 89% (83%) of the children had an interocular difference of maximum 1 line for single (crowded) Lea symbols. The youngest child whose visual acuity could be assessed with Lea symbols was 23 months old. Almost every child older than 30 months could be tested with Lea symbols. Lea acuity higher than 1 and an interocular difference less than 2 lines is not suspect for amblyopia. Children with a difference of more than one line should be reexamined.

Preliminary report: Examination of young children with Lea symbols

BACKGROUND. Lea symbols are highly sensitive for detection of amblyopia in cooperative patients. They are favorable for visual acuity assessment in childhood. Therefore, we assessed age-related normal values and interocular differences of Lea symbol visual acuity. METHODS/PATIENTS. We reexamined 50 out of 193 children aged 21 months to 7 years who came for a routine pediatric examination between January and November 1999. Lea symbol acuity (Lea Symbols Single Symbol Book (LS) and Lea 15-Line Folding Distance Chart (CLS)) and Landolt-C acuity (single (LC) and crowded with 2.6' inter-optotype distance (LC 2.6 )) were measured. A three out of four criterion was used. Strabismus and any organic eye disease were excluded by orthoptic and ophthalmologic examination, consisting of biomicroscopy, ophthalmoscopy, retinoscopy or refractometry, cover test or Hirschberg test and Lang Stereotest. RESULTS. Only 26% of the parents (50 out of 193) accepted an examination in our hospital. In 35 (32) of the 50 children, visual acuity could be measured in both eyes seperately with single (crowded) Lea symbols, while 26 (25) children could be examined in both eyes monocularly with the Landolt-C with single (crowded) optotypes. Except for one 3-year-old boy, all of the children older than 30 months could be tested with single Lea symbols. Lea acuity surpassed Landolt acuity. The difference was about 1.5 lines (1.5 dB) for both the single and the crowded optotypes. In 63% (69%) of the children who could be tested monocularly, LS acuity (CLS acuity) was higher than 0.8 (0.63). 89% (83%) of the children had an interocular difference of maximum 1 line for single (crowded) Lea symbols. CONCLUSIONS. The youngest child whose visual acuity could be assessed with Lea symbols was 23 months old. Almost every child older than 30 months could be tested with Lea symbols. Lea acuity higher than 1 and an interocular difference less than 2 lines is not suspect for amblyopia. Children with a difference of more than one line should be reexamined.

Refraction referral criteria for Hong Kong Chinese preschool children.

The major types of ametropia and visual problems for Hong Kong Chinese and Caucasian children are different. Consequently, the referral criteria developed for Caucasian children may not be applicable to Hong Kong children. Results of our study suggested that the referral criteria for Hong Kong children should be set as hyperopia of > or = +2.0 D, myopia of > or = 1.0 D, astigmatism of > or = 1.0 D and anisometropia of > or = 1.25 D. Sensitivity using only these criteria for abnormal refraction in identifying children with amblyopia, esotropia, exotropia and subnormal vision (< 6/12) was respectively 100%, 84.6%, 45.2% and 95.7%. The overall sensitivity for the identification of visual problems was 86.1% and the overall specificity was 76%. If a cover test or a Hirschberg test was introduced into the screening battery so that all the strabismic cases were identified. the overall sensitivity would increase to 98.6%.

Corneal topography and the Hirschberg test

A simple trigonometric analysis of the Hirschberg test with the assumption that the corneal surface is spherical predicts a sinusoidal dependence of the corneal reflex displacement on the angle of ocular rotation. A comparison with corneal reflex photographs demonstrates that at angles larger than 50 prism diopters (26 deg) the reflex displacements are larger than predicted by the spherical model. This discrepancy may be accounted for by incorporating a more general description of the corneal topography into the geometric analysis. The linear Hirschberg relation that is seen in typical data is accounted for by a relative flattening of the peripheral cornea by ~ 20% of the apical curvature. This geometric analysis of the functional dependence of the Hirschberg relation on the corneal topography can be expressed as an integral equation. Differentiation yields a second-order differential equation for the corneal topography in terms of the Hirschberg data. If the Hirschberg relation is assumed to be linear, a quadratic dependence is found for the corneal curvature. A similar differential approach can be formulated for the Placido disk. In this sense the corneal topography problem given in terms of Placido disk data is shown to be wellformulated. The relative simplicity of the Hirschberg geometry is seen to stem from the alignment of the light source with the eye of the observer.

Rastreio visual em crianças.

The Early Visual Screening (EVS) before verbal communication and, certainly, before one year old, is essential to prevent strabismus and/or amblyopia. We consider the PREFERENTIAL LOOKING (PL) for visual acuity determination and screening of the amblyopia and the PHOTOREFRACTION (VIDEO-REFRACTION: VPR-1) for refractive screening, adequated methods for Early Visual Screening. We suggest that these two technics are used as EVS methods, four times in childhood (newborn, 6-8 weeks, 6-8 months, 18-24 months) performed by an Ophthalmologist at a Pilot Health Center of the National Health Service. The classic methods of visual screening such as: child's reaction to the eye occlusion, pursuit movements, STYCAR balls and miniature toys, Cover test, Hirschberg test, red fundus reflex, anterior segment examination, each of these used according to the child's age, must be performed by an Ophthalmologist. We think they are a positive alternative until we are able to use the PREFERENTIAL LOOKING and VIDEO-REFRACTION in Early Visual Screening. In the kindergarten and primary school the ASTENOPIC complaints due to hipermetropia, minor astigmatism and convergent deficit as well as chronic inflammation of the anterior segment eyelids and anexus, can be related with poor school performance more than with strabismus or myopia.(ABSTRACT TRUNCATED AT 250 WORDS)

The Hirschberg Test

The results of this study indicate that the axial length is not strongly associated with the Hirschberg formula, and therefore the axial length does not have to be considered when measuring an ocular deviation with the Hirschberg test. This study does demonstrate an association between the radius of curvature of the cornea and the Hirschberg formula. For patients with keratometer readings below 46 D, the use of the standard Hirschberg formula, 1 mm = 22 delta, is appropriate. For patients with keratometer readings greater than 46 D, and with deviations greater than about 30 delta, the use of the Hirschberg formula, 1 mm = 27 delta, is more appropriate. When performing the Hirschberg test on infants up to about 2 months of age, the use of the higher Hirschberg formula would probably be more appropriate because this age group often has higher keratometer readings.

Photographic method for Brückner and Hirschberg testing.

An apparatus for strabismus detection was designed to allow photographing fundus and corneal reflexes for Brückner and Hirschberg testing, respectively. Photographs of adult subjects with simulated strabismic deviations were viewed by two groups of observers, optometry students and optometry faculty. In general there was no significant difference in testing results between the two groups. Subject error produced unreliable Brückner results. However, Hirschberg testing was effective approximately 80% of the time in detecting a deviating eye in strabismus of magnitudes of about 5 delta. Anisometropia in Brückner testing was also investigated. Magnitudes of 2.00 D or greater significantly affected results. Clinical application of the photographic Hirschberg test may have potential value as a screening method. The photographic Brückner test is not recommended for adults; its reliability in children requires investigation.

The Hirschberg Test

Though the Hirschberg test has been used for over a 100 years, several different formulas are still being recommended and used clinically to determine the amount of a given ocular deviation. The purpose of this study was to obtain a double-masked clinical evaluation of the Hirschberg test. Several strabismic patients were evaluated by one investigator using the alternate cover test and by another investigator using a photographic Hirschberg procedure in a double-masked procedure. It was determined that the Hirschberg test can be used for strabismic patients of all ages and that the most appropriate formula to use is 1 mm = 22 delta.

Vision and Eye Screening in Finland an Overview

In Finland the public health authorities recommend that a child's visual development should be checked four times during the first year of life, then once a year. During the first year attention is paid to developmental delays and to development of normal eye muscle control. Photorefractive screening of infants between ages 9 to 18 months is recommended but not yet executed except for a few limited pilot studies.At four and six years, testing includes visual acuity measurement using a line test at a distance of three meters, Hirschberg's test, and a cover test. Screening of deaf children and children with cerebral palsy requires new techniques. Screening of mentally retarded children uses informal play situations and new tests such as BUST-LH playing cards and LH-DOMINO plus involvement of day care personnel in observation. Screening at school age is for refractive errors. Introduction of the near visual acuity test has decreased the number of referrals.

Intraoperative adjustment of eye muscle surgery. Correction based on eye position during general anesthesia.

During general anesthesia, the eye position of patients with strabismus, measured by Krimsky's test at 1 m, 30 minutes after induction, has a linear correlation with the eye position measured clinically preoperatively. A similar study was performed on 77 patients; however, Hirschberg's test was used for simplicity and was performed as soon as the patient was in a surgical plane of anesthesia. We confirmed that there was a linear correlation. We also adjusted the surgery performed in seven cases where the test was anomalous, ie, when the eye position under anesthesia was more than 15 prism diopters more or less than expected based on preoperative clinical measurements. We did approximately 1 mm more or less surgery than we had planned on each eye muscle. This significantly improved the final results in anomalous cases. Patients with anomalous tests who did not have such adjustments had significantly poorer results.

Brückner Test

Brückner, in 1962, published a paper in German describing a "trans-illumination" test extremely useful in the diagnosis of small angle deviations and amblyopia in young uncooperative children. A bright coaxial light source, such as a direct ophthalmoscope, is used. Both eyes of the patient are simultaneously illuminated from approximately one meter distance. First, the position of the corneal light reflex, (Hirschberg test), along with brightness difference of the fundus reflex as seen in the pupil through the ophthalmoscope, is evaluated. When strabismus is present. the fixing eye has a darker reflex than the deviated eye. The second step evaluates pupil size, pupil reaction, and fixation movement of the eyes on "successive" illumination of one eye at a time. This is useful in detecting amblyopia.

Ocular rotation and corneal reflexes (author's transl)

The location of the corneal reflex (Purkinje's first image) produced by an electronic flash was studied at various degrees of ocular rotation both in adduction and abduction. A statistical analysis of the results showed a good correlation between the decentration of the corneal reflex and the degrees of ocular rotation. The results thus obtained give an experimental basis to the clinical use of the so-called Hirschberg test for measuring the strabismus angle.

A New Approach to the Hirschberg Test

Forty patients with horizontal strabismus were examined in order to establish a correlation between measurements obtained by the alternate cover under the amblyoscope and measurements made by passively placing the corneal reflex in symmetry of that of the fixating eye. In order to reduce errors, the pupils were constricted to two mms and a very intense and bright one mm corneal reflex produced. Both measurements were very similar and a correlation of r=0,94 was found. Accuracy was significant at the p=0,005 level.