Aniseikonia of central serous chorioretinopathy]

Central serous chorioretinopathy (CRS) is one of the typical diseases that accompany micropsia. However very little is known about micropsia of CRS, because of the difficulty to measure "aniseikonia" in terms of micropsia. Aniseikonia in 65 cases of CRS was measured quantitatively by Awaya's New Aniseikonia Tests (NAT). The tests were performed at two different distances of 40 cm (visual angle: 6 degrees) and 20 cm (12 degrees) and under 4 meridians of the halfmoon on NAT, horizontal, 45 degrees, vertical and 135 degrees, respectively. The mean value of aniseikonia under each testing condition was as follows: 6 degrees horizontal -3.13%, 45 degrees -2.56%, vertical -2.13%, 135 degrees -2.57%, 12 degrees; horizontal -1.38%, 45 degrees -1.69%, vertical -1.84%, 135 degrees -1.50%. At 6 degrees aniseikonia is larger in the horizontal meridian than in the vertical with statistical significance (t-test, p less than 0.05), while at 12 degrees aniseikonia is smaller than at 6 degrees and shows no particular tendency in terms of meridian. The phenomenon observed at 6 degrees may be what is called "oriented metamorphopsia".     

运用唾液腺治疗重症干眼的应用解剖

背景唾液腺移植或导管转位可提供持续性分泌的、生理性的泪液替代物,为重症干眼的理想治疗方法,但其相关解剖学资料较少,且一些研究中的结论尚存在争议,限制了其在临床应用中的改良和推广。目的探讨三大唾液腺移植或其导管移位治疗重症干眼的解剖学基础、手术可行性及各自的优缺点,为进一步的临床应用提供依据。方法在手术显微镜辅助下对34侧颈动脉灌注红色乳胶的成人头颈部标本进行解剖,观察面神经腮腺外分支与腺体的关系,三大唾液腺的形态、大小,导管的长度和外径,追寻其血供来源及分支走行、血管外径、毗邻关系等,并对眼眶周围及额面部血管进行解剖,寻找可供吻合的受区动静脉。在人体标本上模拟腮腺导管转位、下颌下腺及舌下腺游离移植手术。结果腮腺导管位置较固定,导管长度为（4．20±1．10）cm,外径为（0．60±0．30）cm,腮腺导管转位术部分需用颊黏膜或静脉等做导管延长,术中应避免损伤面神经颊支、颧支和颞支;下颌下腺移植术,血管蒂为面血管,外径为（2．70±0．28）mm,移植血管蒂长（1．90±0．30）cm,受区血管为颞浅血管;舌下腺移植术,血管蒂为舌下血管（30侧,占88．2％）或颏下血管（4侧,占11．8％）,其外径分别为（1．92±0．36）mm和（1．96±0．54）mm,移植血管蒂长分别为（2．60±1．10）cm和（3．50±0．40）cm,受区血管为颞浅血管额支,本组中3侧标本舌下腺阙如,占8．8％。结论基于解剖学研究,三大唾液腺移植或其导管移位治疗重症干眼是可行的,并各具优势。腮腺导管转位和下颌下腺移植已应用于临床,舌下腺移植尚需动物实验进一步证实其应用价值。     

Arteries of visual cortex

The purpose of the study was to point out the arterial branches that are supplying the visual cortex. This study was carried out on 100 brains, fixed in formaldehid 10% and dissected under the surgical microscope; 20 of them were at first injected with colored nitrolac. It was observed the origin, relationships and distribution of the arterial branches, which supply these areas. The data obtained reveal that: medial face of the visual cortex receives branches from the posterior cerebral artery (throughout its collaterals: calcarine artery 100%, parietooccipital artery 96% and posterior temporal artery 92%; its lateral surface receives cortical branches from the middle cerebral artery (100%) and its inferior surface is irigated from collaterals of the posterior temporal and temporo-occipital arteries (100%). Some of the branches penetrate directly the visual cortex perpendiculary and others form at first, a superficial, pial network. The knowledge of arterial variants which supply the visual areas is very important for ophthalmologists, radiologists, neuroophthalmologists, neurosurgeons, for recognising their vascular damage in some complex neuroophthalmologic syndroms.     

The pigeon's eye viewed through an ophthalmoscopic microscope: orientation of retinal landmarks and significance of eye movements

The retina of live, anaesthetized pigeons was inspected with an ophthalmoscopic microscope mounted on a goniometer. Retinal landmarks (optic axis, pecten, fovea, border between the yellow and red field) and the ora terminalis were projected into the visual field of the eye and related to existing data. The resting position of the eye is determined by an orientation of the pecten 45 degrees to the horizontal plane and the optic axis pointing to the horizon with an azimuth angle of 70 degrees relative to the bill. The binocular overlap is maximal (approximately 30 degrees) some 15 degrees above the eye-bill axis. In the resting position of the eye the red field is directed to the lower frontal visual field with only marginal binocular overlap. Binocular overlap of the area dorsalis with the red field, however, during frontal fixation is brought about by eye movements in the range we have demonstrated. The fixation point is 10 degrees below the eye-bill axis.     

Sphincter activity in retinal arterioles feeding the deeper capillary layer in pig

PURPOSE: To determine whether a sphincter-like control point is present in 90 degrees branches of the retinal vasculature. Such a control point could selectively control retinal blood flow to the deeper capillary layers. METHODS: A microperfusion system was used in which porcine retinal arteries with intact branches were cannulated and perfused intraluminally at physiological flow rates. The vasoactive response of the proximal and distal regions of either 90 degrees -or Y-type branches to intraluminal potassium (124 mM) were monitored simultaneously in real-time. RESULTS: The proximal region of the 90 degrees branches demonstrated a localized vasoconstriction when compared to the more distal region (p < 0.0001). In contrast, the Y branches contracted evenly along their length. CONCLUSIONS: The localized vasoactivity near the branch point of the 90 degrees -type branches may explain previous observations of so-called sphincter-like activity in these vessels. These sphincters may selectively regulate blood flow to the deeper retinal capillary layer.     

"Erroneous orthograde" direction of flow in the supratrochlear artery as a cause of Doppler ultrasound diagnostic error in severe (filiform; 90%) stenosis of the carotid bifurcation]

Author reports on mistake in Ultrasound-Doppler-Sonography by an neurologist. A 82-year-old women with leftside Amaurosis fugax was referred by her family doctor, internist. Neurological examination, above all Doppler-Sonography, results in "normal findings". Examination by author however detected filiforme stenosis of left internal carotid artery in spite of "orthograde" direction of blood-flow in final branches of ophthalmic artery. This perhaps was the cause of neurological misdiagnosis.     

Estimating squint angle according to the degree of refixation saccades. Model trial fixation saccades]

BACKGROUND: Objective, linear strabismometric methods are used preferentially to assess the eye alignment in patients with bad eyesight or with a deeply amblyopic eye, and also in uncooperative subjects, for instance children. The common point of these methods is that a distance must be measured or estimated, from which the eye rotation, or alignment, is computed through a conversion factor, the angular ratio. Such a ratio was introduced by Hirschberg in the 19th century. The purpose of the study was to examine the influence of the size of angular ratios and examiners influence upon the accuracy of estimation of eye alignment from the limbus position. METHODS: As an experimental test, 9 trained examiners estimated the amount of refixation movements between 0.5 degree and 26 degrees (1 cm/m and 48.8 cm/m). These refixation movements were simulated by a test person who executed fixation saccades in front of a tangent scale designed for a distance of 2.5 m. RESULTS: The magnitude of a refixation movement was estimated best by looking at the limbus shift, with a ratio of about 5 degrees/mm (8.7 cm/m/mm), and an accuracy of +/- 2 degrees (3.5 cm/m) (95% confidence interval) was reached for refixation movements up to +/- 5 degrees (8.7 cm/m). The threshold for detection of microtropia reached about 0.5 degree (1 cm/m). Accuracy was limited by two factors: the difference between the individual and average angular ratio, and estimating errors. CONCLUSIONS: Experienced examiners estimate the angle of strabismus from the magnitude of refixation movements up to +/- 5 degrees (8.7 cm/m) almost as accurately as with the prism and cover test.     

A simplified approach to the treatment of Duane's syndrome

INTRODUCTION: To report the results of a large series of patients undergoing treatment for Duane's syndrome. METHODS: Patients with Duane's syndrome undergoing strabismus surgery of a horizontal muscle recession procedure, medial rectus recession for an esodeviation or lateral rectus recession for an exodeviation, in order to correct an abnormal head position (AHP) and a significant tropia in primary position were identified. Amount of recession varied with the angle of deviation in forced primary position, versions and ductions, and intraoperative forced ductions. Elimination of AHP was used as a criterion for success. RESULTS: Fifty nine patients were treated with either unilateral or bilateral medial or lateral rectus recession. Mean follow up was 3.1 years. Ninety three percent achieved a postoperative alignment of < or =15 degrees AHP, 66% achieved < or =5 degrees AHP. Only three patients, two from the unilateral Type II group and one from the bilateral combined Types I and II group, went on to have a second procedure for a noticeable residual AHP. CONCLUSIONS: Success (good to excellent results) of horizontal muscle recession was achieved in 93% of patients. Unilateral or bilateral horizontal rectus muscle recession offers a simple and effective surgical option for eliminating AHP and is our treatment of choice in patients with Duane's syndrome.     

Filling-in along horizontal and vertical meridians

PURPOSE: Filling-in is not homogeneous across the visual field; rather, fading time (FT) varies with eccentricity and polar angle. The reasons for this are unclear. The authors investigated FT along horizontal and vertical meridians in central and peripheral visual fields for luminance-defined targets, comparing Weber contrast sensitivity (CSw). They also compared cone-mediated and rod-mediated filling-in with previously described photoreceptor densities. This represents the first investigation into rod-mediated filling-in. METHODS: Fading times were recorded in nine volunteers using luminance-defined stimuli at eccentricities of 0 degrees , 2.5 degrees , 5 degrees , 10 degrees , and 20 degrees for high-contrast stimuli and 0 degrees , 1.25 degrees , 2.5 degrees , 3.75 degrees , and 5 degrees for low-contrast stimuli and were compared with CSw at each location. Fading times were also recorded at 0 degrees , 2.5 degrees , 5 degrees , 10 degrees , and 20 degrees using red-green stimuli and at 5 degrees , 10 degrees , and 20 degrees under dark-adapted conditions and compared with cone and rod densities in the nasal, temporal, superior, and inferior hemimeridians. RESULTS: Consistent anisotropy was evident in central and peripheral fields for luminance-defined targets and for chromatic targets, with horizontal meridians taking longer to fill in. The same pattern was observed in CSw and the previously described cone density. Log FT and CSw were correlated irrespective of visual field location. The ratio of rod-mediated FT to rod density decreased with eccentricity. CONCLUSIONS: Anisotropy between horizontal and vertical meridians for FT is consistent in central and peripheral fields, reflecting patterns in CSw and cone density. This is discussed in the context of cortical processes underlying filling-in. For rod-mediated filling-in, more peripheral eccentricities are characterized by reduced FTs in relation to rod density.     

视神经鞘减压术有关动脉的应用解剖

目的为视神经鞘减压术提供有关动脉解剖学资料。方法采用显微解剖和血管铸型技术对30个甲醛固定成人尸头和4个新鲜尸头视神经的鞘动脉等进行观察。结果鞘动脉可分为视神经管内支和眶内支。眶内支主要来自眼动脉第2段，占63．33％，也可发自眼肌动脉干等，其入鞘点多在眶内部鞘的后1／3段的上面或内侧面。管内支多从眼动脉的内侧壁发起，行于视神经腹侧面，以1支者多见，占61.67％，2支者占11.67％，3支者占5.00％。结论管内视神经鞘切开部位在鞘的外上壁或内上壁较安全，眶内鞘切开部位选在鞘的外侧面较好。     

Arterial blood supply and innervation of the rectus muscles of the eyeball

The authors report on the arterial blood supply and the innervation of the rectus muscles of the eyeball from human orbital dissections. MATERIAL AND METHODS: Hundred human orbits were dissected using a superior approach after arterial injection with colored latex. The different arterial pedicles for each muscle were noted and the nervous supply was studied. RESULTS: The arterial blood supply of the rectus muscles comes from different branches of the ophthalmic artery, usually the inferior muscular artery, the lacrimal artery, the superior muscular artery when it exists, and by small branches arising from the ophthalmic artery. The superior rectus is supplied by branches of the ophthalmic artery and the lacrimal artery (1 to 5 pedicles). The medial rectus is supplied by branches of the ophthalmic artery and the inferior muscular artery (5 to 9 branches). The inferior muscle rectus is principally supplied by the inferior muscular artery (4 pedicles) and the lateral muscle is supplied by the lacrimal artery or the lateral muscular artery (3 to 6 branches). For innervation, the abducens nerve supplies the lateral rectus; the other muscles are supplied by the oculomotor nerve whose superior branch supplies the superior rectus and whose inferior branch, supplies the inferior and medial rectus. DISCUSSION: The arterial blood supply is variable. The arteries which lie near the rectus muscles usually supply one or more branches to the muscles. The arteries go into the muscles through their conal side. This arterial supply is at the posterior part of the muscle. Innervation, in contrast, is very constant and fixed. CONCLUSION: The arterial blood supply to the rectus muscles is variable but always substantial. The pedicles are numerous, often 3 to 5 for each muscle. Innervation is fixed and constant.     

Asymmetry of retinal arteriolar branch widths at junctions affects ability of formulae to predict trunk arteriolar widths

PURPOSE: To describe a revised formula for the estimation of retinal trunk arteriole widths from their respective arteriolar branch widths that improves the summarizing of retinal arteriolar diameters. METHODS: A group of young, healthy individuals underwent retinal photography and arteriolar and venular branching points were identified. Vessel widths of the vessel trunks and their branches were determined. The relationship between the branching coefficient (BC; quotient of the area of the branch and trunk vessels) and the asymmetry index (AI) of the vessel branches was explored. The result was used to formulate a new BC. To test the new BC, a second group of young, healthy individuals also underwent retinal photography. Arteriolar branching points were identified, and the trunk and branch arteriolar widths were recorded. This "revised" BC was compared against the gold standard of the BC as a constant value (1.28), as well as a theoretical formula for the BC that includes the angle between the two vessel branches. RESULTS: The BC of arterioles (but not venules) related to the AI (R = 0.275, P = 0.0001; BC arterioles = 0.78 +/- 0.63 . AI). In the second group, the mean arteriolar trunk diameter was 15.56 pixels. The linear regression model for the arteriolar BC was superior to the BC constant of 1.28 (mean difference between estimated and calculated trunk vessel width was 2.16 vs. 2.23 pixels, respectively). The model based on the angle between the branch arterioles was the least accurate (3.43 pixels). CONCLUSIONS: A revised formula has been devised for the arteriolar BC using a linear regression model that incorporates its relationship to the AI. Further studies using this refined formula to calculate the BC are needed to determine whether it improves the ability to detect smaller associations between the retinal vascular network and cardiovascular disease.     

The morphology of the palpebral fissure in different directions of vertical gaze.

PURPOSE: The purpose of this study is to investigate the normative morphology of the palpebral fissure by measuring a range of biometric eye dimensions for a population of young subjects through analysis of digital images in primary gaze and two typical angles of downward vertical gaze. Palpebral fissure characteristics are clinically important in areas such as contact lens practice. METHODS: High-resolution digital images were taken of 76 young subjects with a range of refractive errors in primary gaze and 20 degrees and 40 degrees downward gaze. The digital images were analyzed to ascertain a range of biometric measures of the palpebral fissure for each subject in each angle of gaze. Repeated-measures analysis of variance was used to investigate changes occurring in the palpebral fissure dimensions with vertical angle of gaze. RESULTS: Highly significant changes were found to occur in the horizontal and vertical palpebral fissure dimensions, the palpebral fissure angle, and the eyelid contour as a function of angle of gaze. The palpebral fissure narrows in the vertical dimension (from an average vertical palpebral aperture width for white subjects in primary gaze of 9.7+/-1.2 mm to an average width of 6.4+/-1.1 mm in 40 degrees downgaze), shortens in the horizontal dimension (from average horizontal palpebral aperture width of 27.1+/-1.5 mm in primary gaze to an average of 25.6+/-1.8 mm in 40 degrees downgaze), and becomes more "down-slanted" with increasing downward gaze. CONCLUSIONS: Highly significant changes to the palpebral fissure dimensions occur in downward vertical gaze. These changes are important because many visual tasks are performed in downward gaze. These findings have implications for the management of lid anomalies and for contact lens fitting and design.     

Feasibility of prismatic correction of microesotropia using the measuring and correcting methodology by H.-J. Haase

BACKGROUND: The "Measuring and Correcting Methodology after H.-J. Haase" is based on the assumption that a minute deviation from the orthovergence position (fixation disparity) indicates a difficulty to overcome a larger "vergence angle of rest". Objective recordings have, however, revealed that the subjective tests applied in the "Measuring and Correcting Methodology after H.-J. Haase" can mislead to the assumption of a fixation disparity, although both eyes are aligned exactly to the fixation point. Question: How do patients with an inconspicuously small, yet objectively verified strabismus react to the "Measuring and Correcting Methodology by H.-J. Haase"? METHODS: Eight patients with a microesotropia between 0.5 and 3 degrees were subjected to the "Measuring and Correcting Methodology after H.-J. Haase. RESULTS: In all 8 patients, the prisms determined with the Cross-, Pointer- and Rectangle Tests increased the angle of squint, without reaching a full correction: the original angle prevailed. In the Stereobalance Test, prisms did not reduce the 100 % preponderance of the non-squinting eye. The stereoscopic threshold was between 36 and 1170 arcsec in 7 out of the 8 subjects, and above 4000 arcsec in 1 subject. CONCLUSIONS: (1) In all 8 patients, prisms determined with the "Measuring and Correcting Methodology by H.-J. Haase" increased the angle of strabismus, without reaching bifoveal vision. This uniform result suggests that primary microesotropia cannot be corrected with the "Measuring and Correcting Methodology after H.-J. Haase" (2) A lacking contribution of the strabismic eye to the recognition of a lateral offset between stereo objects, as determined with the Stereobalance Test, does not imply a lack of binocular stereopsis.     

Visual fields and eye movements in a harbor seal (Phoca vitulina)

The boundaries of the visual fields of a harbor seal were measured using static perimetry. In the seal lying on a plane surface (fixation point "0 degrees" straight ahead at eye-level), the visual field with fixed eyes extended over 208 degrees horizontally and reached from -12 degrees to +69 degrees vertically. The binocular visual field amounted to 67 degrees. Eye movements of 12 degrees (+/-2) degrees to both sides and 64 degrees upwards could be induced. In the seal performing eye movements, a visual field of 210 degrees in the horizontal plane and 121 degrees to the dorsal side was determined. From the measured eye movements, a visual field of 232 degrees in the horizontal plane appears possible.     

Particular aspects of the arterial blood supply of the optic radiations

The purpose of this study was to point out the arterial branches that are supplying the optic radiations. The study was carried out on 100 human brains, fixed in formaldehid 10% and dissected under the surgical microscope; 20 of them were at first injected with colored nitrolac. It were observed the origin, traject, relationships and distribution of the arterial branches which supply this optic fibers. The data obtained reveal that: the anterior segment of the optic radiations receives branches from the anterior choroidal artery (100%), middle cerebral artery (83%), thalamogeniculate arteries (78%) and posterior and lateral choroidal arteries (27%); the middle segment of the optic radiations is supplied by arterial branches from the middle cerebral artery (100%), parieto-occipital artery (84%), anterior and middle temporal arteries (36%); the posterior segment of the optic radiations receives branches from the middle cerebral artery (100%) and posterior cerebral artery (100%). All this branches penetrate directly the optic fibers. The knowledge of arterial variants which supply the optic radiations are for great interest for radiologists, neuroophthalmologists, neurosurgeons, for recognising their vascular damage in some complex neuroophthalmologic syndroms.     

Processes involved in oculomotor adaptation to eccentric reading

PURPOSE: Adaptation to eccentric viewing in subjects with a central scotoma remains poorly understood. The purpose of this study was to analyze the adaptation stages of oculomotor control to forced eccentric reading in normal subjects. METHODS: Three normal adults (25.7 +/- 3.8 years of age) were trained to read full-page texts using a restricted 10 degrees x 7 degrees viewing window stabilized at 15 degrees eccentricity (lower visual field). Gaze position was recorded throughout the training period (1 hour per day for approximately 6 weeks). RESULTS: In the first sessions, eye movements appeared inappropriate for reading, mainly consisting of reflexive vertical (foveating) saccades. In early adaptation phases, both vertical saccade count and amplitude dramatically decreased. Horizontal saccade frequency increased in the first experimental sessions, then slowly decreased after 7 to 15 sessions. Amplitude of horizontal saccades increased with training. Gradually, accurate line jumps appeared, the proportion of progressive saccades increased, and the proportion of regressive saccades decreased. At the end of the learning process, eye movements mainly consisted of horizontal progressions, line jumps, and a few horizontal regressions. CONCLUSIONS: Two main adaptation phases were distinguished: a "faster" vertical process aimed at suppressing reflexive foveation and a "slower" restructuring of the horizontal eye movement pattern. The vertical phase consisted of a rapid reduction in the number of vertical saccades and a rapid but more progressive adjustment of remaining vertical saccades. The horizontal phase involved the amplitude adjustment of horizontal saccades (mainly progressions) to the text presented and the reduction of regressions required.     

Development of the standard reference plane for the Heidelberg retina tomograph

Background: Topometry of the optic disc is the quantitative assessment of the structure of the optic nerve head by means of three- dimensional parameters. The parameter values depend on definitions of intraocular reference planes. Purpose: To describe the development of intraocular reference planes in laser scanning tomography for the Heidelberg Retina Tomograph (HRT) using image intrinsic data with a fixed offset reference plane (320 μm) and to present a contour-line-based ”flexible” standard reference plane (”SRP”) for calculation of intrapapillary stereometric parameters taking the interindividual variability of optic disc topography into account.Methods: Ten-degree triple images were obtained by laser scanning tomography from 99 glaucoma eyes and 180 normal eyes. The images were evaluated to assess the variability of height measurements of an optic disc border contour-line segment (6° width) corresponding to the site of the papillo-macular bundle as indicated by the average optic disc surface inclination angle. Results: The average optic disc surface inclination angle was –7°±3° below the horizontal meridian (0°). The 6° wide contour-line segment for the SRP was chosen according to the average surface inclination angle (–10° to –4°). The reproducibility of the SRP-segment height measurements was 16.0±10.8 μm for normal eyes and 23.4±18.0 μm for glaucoma eyes. To ensure that the automatic reference level determination for intrapapillary parameters remained below the disc border height, we defined the SRP level at a 50 μm offset (>2 SD of average segment height reproducibility in glaucoma) added to the individual height position of the 6° contour line segment. Conclusion: The flexible standard reference plane allows for automatic determination of intrapapillary variables once a disc border contour line is interactively defined. In contrast to a fixed offset reference plane (e.g. 320 μm below the mean retina height), the interindividual variability of optic disc topography (oblique insertion, glaucomatous surface flattening) is respected at the cost of the need for an accurate optic disc border outline. Received: 9 March 1999 Revised: 26 August 1999 Accepted: 29 September 1999     

Astigmatism outcomes of horizontal temporal versus nasal clear corneal incision cataract surgery

PURPOSE: To compare the short- and long-term astigmatism outcomes after cataract surgery using temporal clear horizontal corneal incisions and nasal horizontal clear corneal incisions. SETTING: Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore, Maryland, USA. METHODS: This retrospective study included a consecutive series of eyes having phacoemulsification with implantation of a 6.0 mm foldable acrylic intraocular lens through a 3.5 mm horizontal clear corneal incision at 180 degrees (temporal incision in right eyes, nasal incision in left eyes). Astigmatism was measured by keratometry readings before surgery and 6 weeks and 12 months postoperatively. RESULTS: The mean preoperative astigmatism in the 178 eyes (94 right, 84 left) of 161 patients was 0.78 diopter (D); 54.5% of eyes had against-the-rule (ATR) astigmatism, 22.5% had with-the-rule (WTR) astigmatism, and 14.0% were astigmatically neutral. A significant shift toward WTR astigmatism occurred postoperatively. At 6 weeks, 48.3% of eyes had WTR astigmatism and 23.0% had ATR astigmatism. At 12 months, 43.8% had WTR astigmatism and 25.8% had ATR astigmatism. Vector analysis revealed a mean surgically induced astigmatism (SIA) of 1.17 D at 6 weeks and 1.04 D at 12 months. The side of the incision significantly affected SIA. At 6 weeks, temporal incisions yielded a mean SIA of 0.74 D and the nasal incisions, of 1.65 D. This trend in SIA persisted at 12 months: 0.71 D for temporal incisions and 1.41 D for nasal incisions. CONCLUSIONS: Cataract surgery using a horizontal clear corneal incision induced WTR astigmatism 6 weeks and 12 months postoperatively. Temporal incisions induced significantly less astigmatism than nasal incisions.