- Email: [email protected]
Near-infrared spectroscopy of the visual cortex in unilateral optic neuritis
early stages, and that in the later stages it could increase in height to cause photoreceptor dysfunction and visual loss. We think these new OCT findings would help in better understanding of the condition. REFERENCES
1. Kraushar MF, Margolis S, Morse PH, Nugent ME. Pseudohypopyon in Best’s vitelliform macular dystrophy. Am J Ophthalmol 1982;94:30 –37. 2. Pierro L, Tremolada G, Introini U, Calori G, Brancato R. Optical coherence tomography findings in adult-onset foveomacular vitelliform dystrophy. Am J Ophthalmol 2002;134: 675– 680. 3. Men G, Batioglu F, Ozkan SS, Atilla H, Ozdamar Y, Aslan O. Best’s vitelliform macular dystrophy with pseudohypopyon: an optical coherence tomography study. Am J Ophthalmol 2004; 137:963–965. 4. Pianta MJ, Aleman TS, Cideciyan AV, et al. In vivo micropathology of Best macular dystrophy with optical coherence tomography. Exp Eye Res 2003;76:203–211. 5. O’Gorman S, Flaherty WA, Fishman GA, Berson EL. Histopathologic findings in Best’s vitelliform macular dystrophy. Arch Ophthalmol 1988;106:1261–1268.
Near-infrared Spectroscopy of the Visual Cortex in Unilateral Optic Neuritis FIGURE 2. (Top) Color fundus photograph of the left eye of the patient showing a shallow cystic lesion over the fovea containing a central yellow material (white arrow). The superior part of the lesion shows atrophic changes. (Bottom) Optical coherence tomography picture (vertical line scan through the fovea) of the left eye of the patient showing a subretinal pigment epithelium conical mound of moderately reflective material (white arrow), which corresponds to the central yellow material seen clinically. Note the mild disruption of the photoreceptor layer overlying the mound.
an earlier stage of the disease than the patient reported by Men and associates. Of note, a similar subretinal pigment epithelium accumulation of material between retinal pigment epithelium and the Bruch’s membrane has been demonstrated histopathologically.5 We also describe the OCT picture of the “scrambledegg” stage that suggests a possible cause of the visual loss experienced at this stage. The disruption of the photoreceptors due to the mass effect of the underlying material could lead to their metabolic dysfunction and thus account for the defective vision experienced in the left eye by our patient. In this case report, we present OCT-based evidence that in the “pseudohypopyon” stage, lipofuscin accumulates in a subretinal pigment epithelium cystic space, at least in the VOL. 139, NO. 2
Atsushi Miki, MD, PhD, Takashi Nakajima, MD, PhD, Mineo Takagi, MD, PhD, Tomoaki Usui, MD, PhD, Haruki Abe, MD, Chia-Shang J. Liu, BA, and Grant T. Liu, MD PURPOSE: To examine the occipital-lobe activation of patients with optic neuritis using near-infrared spectroscopy. DESIGN: Experimental study. METHODS: NIRS was performed on five patients with acute unilateral optic neuritis during monocular visual stimulation. As controls, six normal subjects were also tested in the same manner. RESULTS: In the patients with optic neuritis, the changes in the hemoglobin concentrations (oxyhemoglobin, deoxyhemoglobin, and total hemoglobin) in the occipital Accepted for publication July 22, 2004. From the Division of Ophthalmology and Visual Sciences, Niigata University, Graduate School of Medical and Dental Sciences, Niigata, Japan (A.M., M.T., T.U., H.A.); Department of Neurology, National Niigata Hospital, Kashiwazaki, Japan (T.N.); Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania (C-S.J.L.); Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania (G.T.L.). Inquiries to Atsushi Miki, MD, PhD, Department of Ophthalmology, Niigata University Graduate School of Medicine and Dental Sciences, 1-757 Asahimachi-dori, Niigata 951-8510, Japan; fax: 81-25-227-0785; e-mail: [email protected]
BRIEF REPORTS
353
FIGURE 1. A normal subject. Changes in the hemoglobin concentrations (oxyhemoglobin, deoxyhemoglobin, and total hemoglobin) of the visual cortex in response to the stimulation of the right eye (“R”) are given in arbitrary units. The horizontal axis indicates the time (seconds). “O” indicates the resting period. A consistent response, consisting of an increase in [oxy-Hb], a decrease in [deoxy-Hb], and a small increase in [total-Hb] during monocular visual stimulation of the right eye, delayed by around 10 seconds, is observed throughout the experiment.
lobe were found to be markedly reduced when the clinically affected eyes were stimulated compared with the fellow eyes. The response induced by the stimulation of the affected eye was decreased, even when the patient’s visual acuity improved to 20/20 in the recovery phase. There was no difference in the concentration changes between the two eyes in the control subjects. CONCLUSIONS: NIRS may be useful in detecting visual dysfunction objectively and noninvasively in patients with visual disturbance, especially when used at the bedside. (Am J Ophthalmol 2005;139:353–356. © 2005 by Elsevier Inc. All rights reserved.)
N
We used an OM-100A (Shimadzu Corporation, Kyoto, Japan) near-infrared spectroscopy system, with wavelengths at 780, 805, and 830 nm, to monitor changes in the oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentrations in the occipital lobe, respectively. The inter-optode distance was approximately 3 cm. The algorithm for calculating the hemoglobin concentration has been described elsewhere.5 Light-proof goggles (S10VS, Grass Instruments, Quincy, Massachusetts, USA), flashing at a frequency of 8 Hz, were placed over the subjects’ eyes to provide monocular visual stimulation. Each condition lasted for 30 seconds, and a pair of two conditions was repeated six times for each experiment. A Macintosh-based program, Macstim (David Darby, West Melbourne, Australia), was used to turn the visual stimulation on or off. For statistical analysis, t tests were performed on each subject between the mean values during the two conditions (the right-eye stimulation vs the resting condition, for instance) using SigmaStat (SPSS, Inc., Chicago, Illinois, USA). P ⬍ .05 was considered to be statistically significant. In all six normal subjects, an increase in oxyhemoglobin, a decrease in deoxyhemoglobin, and an increase in total hemoglobin were observed after monocular visual stimulation. In these control subjects, there were no significant differences in activation between the right and left eyes (data not shown). Figure 1 shows representative NIRS time course plots of a normal subject. In all the studies of the patients with unilateral optic neuritis, a significant reduction in activation during the
EAR-INFRARED SPECTROSCOPY (NIRS) IS AN OPTICAL
method to assess dynamic changes in the hemoglobin concentration evoked by brain activity.1– 4 We applied this technique to five patients with unilateral optic neuritis and investigated whether NIRS could detect visual dysfunction objectively in clinically affected eyes. Six healthy volunteers (one man and five women, age 25 to 39 years) with normal vision and five patients with acute unilateral optic neuritis (two men and three women, age 13 to 56 years) were examined. Informed consent was obtained from each subject or patient. This study was carried out with approval from the Institutional Review Board of the National Saigata Hospital. In patient 1, NIRS was measured twice—when the visual acuity in the right eye was 20/200 and 20/40. In patient 2, NIRS was measured three times—when the visual acuity in the right eye was 20/200, 20/40, and 20/20. The other three patients were tested only once.
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FIGURE 2. (Top) Patient 1 (optic neuritis OD). This 23-year-old woman was found to have decreased visual acuity, a relative afferent papillary defect, a central scotoma and a superior altitudinal field defect, and disk swelling in the right eye. “R” and “L” denote the periods of the stimulation of the right and left eyes, respectively. The response was substantially decreased with the stimulation of the affected right eye. At the time of the study, the visual acuity was 20/200 in the right eye. (Bottom) Patient 2 (optic neuritis OD). This 38-year-old man was found to have decreased visual acuity in the right eye with a central scotoma. A diagnosis of optic neuritis was confirmed by the presence of a right relative afferent papillary defect and a slightly swollen right optic disk. Even after recovery (the visual acuity OD was 20/20 at the time of this study), there remains a significant difference in the monocular activation of the visual cortex between the two eyes (i.e., there is a reduced response during the stimulation of the affected right eye).
stimulation of the affected eye was observed compared with the response measured from the fellow eye (Figure 2, top). A significant activation of the visual cortex was detected when the fellow eyes were stimulated in all patients (data not shown). The reduced response from the affected eye was also observed, even when the subject’s visual acuity in the affected eye recovered to 20/20 (Figure 2, bottom). The prominent advantage of NIRS over other methods to assess visual function objectively is that it can easily be VOL. 139, NO. 2
performed at the bedside, making it especially useful for patients with limited mobility. Additionally, NIRS requires little cooperation from the subjects. There is no known health risk from NIRS. Our results demonstrate that a decreased activation of the visual cortex in patients with optic neuritis can be demonstrated when NIRS is used. We are unaware of any previous reports of NIRS in the field of ophthalmology. Although the sensitivity of this method remains to be studied, NIRS may well be a promising method by which to detect visual
BRIEF REPORTS
355
dysfunction in patients with visual deficits both objectively and noninvasively. REFERENCES
1. Kato T, Kamei A, Takashima S, Ozaki T. Human visual cortical function during photic stimulation monitoring by means of near-infrared spectroscopy. J Cereb Blood Flow Metab 1993;13:516 –520. 2. Meek JH, Elwell CE, Khan MJ, et al. Regional changes in cerebral haemodynamics as a result of a visual stimulus measured by near infrared spectroscopy. Proc R Soc Lond B Biol Sci 1995;261:351–356. 3. Villringer A, Chance B. Non-invasive optical spectroscopy and imaging of human brain function. Trends Neurosci 1997;20:435– 442. 4. Ruben J, Wenzel R, Obrig H, et al. Haemoglobin oxygenation changes during visual stimulation in the occipital cortex. Adv Exp Med Biol 1997;428:181–187. 5. Tamura M, Hoshi Y, Okada F. Localized near-infrared spectroscopy and functional optical imaging of brain activity. Philos Trans R Soc Lond B Biol Sci 1997;352:737–742.
FIGURE 1. Color photograph showing marked fat atrophy and sunken appearance of the right eye. Munson’s sign is elicited in down-gaze.
secondary to chronic and persistent eye-rubbing in a healthy child. (Am J Ophthalmol 2005;139:356-357. © 2005 by Elsevier Inc. All rights reserved.)
K
Unilateral Keratoconus in a Child With Chronic and Persistent Eye Rubbing Alexander S. Ioannidis, MRCOphth, Lynne Speedwell, MCOptom, and Ken K. Nischal, FRCOphth PURPOSE: To report a case of unilateral keratoconus in a 7- year-old female, secondary to chronic persistent eyerubbing in the absence of any systemic condition. DESIGN: Observational case report. METHODS: In the case of this child, no organic cause was found to explain the onset of keratoconus other than persistent eye-rubbing in the affected eye. RESULTS: Nocturnal eye padding was instigated and the condition stabilized. She was reviewed over a 2-year period of follow-up. CONCLUSIONS: Eye-rubbing has been implicated in the pathogenesis of keratoconus. Eye-rubbing is also often a feature of a number of conditions linked to keratoconus such as Down syndrome, atopic keratoconjunctivitis, mental retardation, and Lebers’ congenital amaurosis. There are a number of reports linking eye-rubbing and keratoconus in children, typically in relation to these conditions. However, in this case the keratoconus was Accepted for publication July 22, 2004. From the Department of Ophthalmology, Great Ormond Street Hospital for Children, London, United Kingdom (A.S.I., L.S., K.K.N.); and the Department of Visual Sciences, Institute of Child Health, London, United Kingdom (K.K.N.). Inquiries to Ken K. Nischal, Department of Ophthalmology, Great Ormond Street Hospital, Great Ormond Street, London WC1N3JH United Kingdom; fax: 0114-207-829-8647; e-mail: [email protected]
356
AMERICAN JOURNAL
ERATOCONUS IS CHARACTERIZED BY A NONINFLAM-
matory thinning of the cornea. It is considered a corneal ectasia secondary to stromal thinning1 although some have suggested that it is a type of corneal warpage in the mild to moderate forms of the disease.2 A female child presented with unilateral keratoconus, secondary solely to chronic eye-rubbing. A 7-year-old female was referred to our unit because of a history of apparent enophthalmos and reduced visual acuity in the right eye. She was observed rubbing her right eye persistently since the age of 6 months with no history of itchiness or discomfort in the eye. Systemic examination was normal. Her visual acuity was 6/60 in the right and 6/6 in the left eye unaided. There appeared to be some fat atrophy giving the appearance of a sunken orbit with 1 mm of lid retraction on the right side and a deep upper sulcus. On downgaze, there was evidence of Munson’s sign in the right eye (Figure 1). There was no evidence of Vogts striae or a Fleischer ring. On the Hertel exophthalmometer the corneal apices measured bilaterally at 16 mm. There was no evidence of a papillary or follicular reaction on the tarsal conjunctivae bilaterally. Anterior chambers were deep and quiet, and the intraocular pressures were 13 mmHg in both eyes. Fundi were normal. MRI of the orbits was also normal. Keratoscopy revealed a cone inferolateral to the center of the cornea with thinning (384 ) and a high degree of astigmatism in the right eye. Retinoscopy revealed a clear scissor reflex in the right eye and cycloplegic refraction showed that she had a ⫺3.75 to 7.75 cyl ⫻ 15 error in the right eye. There was no refractive error in the left eye. Nocturnal eye padding was initiated to minimize the eye-rubbing episodes. A genetic screen was performed and was found to be normal. Subsequently, she presented with a central corneal scar in the right eye 4 mm in diameter, OF
OPHTHALMOLOGY
FEBRUARY 2005
1. Kraushar MF, Margolis S, Morse PH, Nugent ME. Pseudohypopyon in Best’s vitelliform macular dystrophy. Am J Ophthalmol 1982;94:30 –37. 2. Pierro L, Tremolada G, Introini U, Calori G, Brancato R. Optical coherence tomography findings in adult-onset foveomacular vitelliform dystrophy. Am J Ophthalmol 2002;134: 675– 680. 3. Men G, Batioglu F, Ozkan SS, Atilla H, Ozdamar Y, Aslan O. Best’s vitelliform macular dystrophy with pseudohypopyon: an optical coherence tomography study. Am J Ophthalmol 2004; 137:963–965. 4. Pianta MJ, Aleman TS, Cideciyan AV, et al. In vivo micropathology of Best macular dystrophy with optical coherence tomography. Exp Eye Res 2003;76:203–211. 5. O’Gorman S, Flaherty WA, Fishman GA, Berson EL. Histopathologic findings in Best’s vitelliform macular dystrophy. Arch Ophthalmol 1988;106:1261–1268.
Near-infrared Spectroscopy of the Visual Cortex in Unilateral Optic Neuritis FIGURE 2. (Top) Color fundus photograph of the left eye of the patient showing a shallow cystic lesion over the fovea containing a central yellow material (white arrow). The superior part of the lesion shows atrophic changes. (Bottom) Optical coherence tomography picture (vertical line scan through the fovea) of the left eye of the patient showing a subretinal pigment epithelium conical mound of moderately reflective material (white arrow), which corresponds to the central yellow material seen clinically. Note the mild disruption of the photoreceptor layer overlying the mound.
an earlier stage of the disease than the patient reported by Men and associates. Of note, a similar subretinal pigment epithelium accumulation of material between retinal pigment epithelium and the Bruch’s membrane has been demonstrated histopathologically.5 We also describe the OCT picture of the “scrambledegg” stage that suggests a possible cause of the visual loss experienced at this stage. The disruption of the photoreceptors due to the mass effect of the underlying material could lead to their metabolic dysfunction and thus account for the defective vision experienced in the left eye by our patient. In this case report, we present OCT-based evidence that in the “pseudohypopyon” stage, lipofuscin accumulates in a subretinal pigment epithelium cystic space, at least in the VOL. 139, NO. 2
Atsushi Miki, MD, PhD, Takashi Nakajima, MD, PhD, Mineo Takagi, MD, PhD, Tomoaki Usui, MD, PhD, Haruki Abe, MD, Chia-Shang J. Liu, BA, and Grant T. Liu, MD PURPOSE: To examine the occipital-lobe activation of patients with optic neuritis using near-infrared spectroscopy. DESIGN: Experimental study. METHODS: NIRS was performed on five patients with acute unilateral optic neuritis during monocular visual stimulation. As controls, six normal subjects were also tested in the same manner. RESULTS: In the patients with optic neuritis, the changes in the hemoglobin concentrations (oxyhemoglobin, deoxyhemoglobin, and total hemoglobin) in the occipital Accepted for publication July 22, 2004. From the Division of Ophthalmology and Visual Sciences, Niigata University, Graduate School of Medical and Dental Sciences, Niigata, Japan (A.M., M.T., T.U., H.A.); Department of Neurology, National Niigata Hospital, Kashiwazaki, Japan (T.N.); Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania (C-S.J.L.); Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania (G.T.L.). Inquiries to Atsushi Miki, MD, PhD, Department of Ophthalmology, Niigata University Graduate School of Medicine and Dental Sciences, 1-757 Asahimachi-dori, Niigata 951-8510, Japan; fax: 81-25-227-0785; e-mail: [email protected]
BRIEF REPORTS
353
FIGURE 1. A normal subject. Changes in the hemoglobin concentrations (oxyhemoglobin, deoxyhemoglobin, and total hemoglobin) of the visual cortex in response to the stimulation of the right eye (“R”) are given in arbitrary units. The horizontal axis indicates the time (seconds). “O” indicates the resting period. A consistent response, consisting of an increase in [oxy-Hb], a decrease in [deoxy-Hb], and a small increase in [total-Hb] during monocular visual stimulation of the right eye, delayed by around 10 seconds, is observed throughout the experiment.
lobe were found to be markedly reduced when the clinically affected eyes were stimulated compared with the fellow eyes. The response induced by the stimulation of the affected eye was decreased, even when the patient’s visual acuity improved to 20/20 in the recovery phase. There was no difference in the concentration changes between the two eyes in the control subjects. CONCLUSIONS: NIRS may be useful in detecting visual dysfunction objectively and noninvasively in patients with visual disturbance, especially when used at the bedside. (Am J Ophthalmol 2005;139:353–356. © 2005 by Elsevier Inc. All rights reserved.)
N
We used an OM-100A (Shimadzu Corporation, Kyoto, Japan) near-infrared spectroscopy system, with wavelengths at 780, 805, and 830 nm, to monitor changes in the oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentrations in the occipital lobe, respectively. The inter-optode distance was approximately 3 cm. The algorithm for calculating the hemoglobin concentration has been described elsewhere.5 Light-proof goggles (S10VS, Grass Instruments, Quincy, Massachusetts, USA), flashing at a frequency of 8 Hz, were placed over the subjects’ eyes to provide monocular visual stimulation. Each condition lasted for 30 seconds, and a pair of two conditions was repeated six times for each experiment. A Macintosh-based program, Macstim (David Darby, West Melbourne, Australia), was used to turn the visual stimulation on or off. For statistical analysis, t tests were performed on each subject between the mean values during the two conditions (the right-eye stimulation vs the resting condition, for instance) using SigmaStat (SPSS, Inc., Chicago, Illinois, USA). P ⬍ .05 was considered to be statistically significant. In all six normal subjects, an increase in oxyhemoglobin, a decrease in deoxyhemoglobin, and an increase in total hemoglobin were observed after monocular visual stimulation. In these control subjects, there were no significant differences in activation between the right and left eyes (data not shown). Figure 1 shows representative NIRS time course plots of a normal subject. In all the studies of the patients with unilateral optic neuritis, a significant reduction in activation during the
EAR-INFRARED SPECTROSCOPY (NIRS) IS AN OPTICAL
method to assess dynamic changes in the hemoglobin concentration evoked by brain activity.1– 4 We applied this technique to five patients with unilateral optic neuritis and investigated whether NIRS could detect visual dysfunction objectively in clinically affected eyes. Six healthy volunteers (one man and five women, age 25 to 39 years) with normal vision and five patients with acute unilateral optic neuritis (two men and three women, age 13 to 56 years) were examined. Informed consent was obtained from each subject or patient. This study was carried out with approval from the Institutional Review Board of the National Saigata Hospital. In patient 1, NIRS was measured twice—when the visual acuity in the right eye was 20/200 and 20/40. In patient 2, NIRS was measured three times—when the visual acuity in the right eye was 20/200, 20/40, and 20/20. The other three patients were tested only once.
354
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FIGURE 2. (Top) Patient 1 (optic neuritis OD). This 23-year-old woman was found to have decreased visual acuity, a relative afferent papillary defect, a central scotoma and a superior altitudinal field defect, and disk swelling in the right eye. “R” and “L” denote the periods of the stimulation of the right and left eyes, respectively. The response was substantially decreased with the stimulation of the affected right eye. At the time of the study, the visual acuity was 20/200 in the right eye. (Bottom) Patient 2 (optic neuritis OD). This 38-year-old man was found to have decreased visual acuity in the right eye with a central scotoma. A diagnosis of optic neuritis was confirmed by the presence of a right relative afferent papillary defect and a slightly swollen right optic disk. Even after recovery (the visual acuity OD was 20/20 at the time of this study), there remains a significant difference in the monocular activation of the visual cortex between the two eyes (i.e., there is a reduced response during the stimulation of the affected right eye).
stimulation of the affected eye was observed compared with the response measured from the fellow eye (Figure 2, top). A significant activation of the visual cortex was detected when the fellow eyes were stimulated in all patients (data not shown). The reduced response from the affected eye was also observed, even when the subject’s visual acuity in the affected eye recovered to 20/20 (Figure 2, bottom). The prominent advantage of NIRS over other methods to assess visual function objectively is that it can easily be VOL. 139, NO. 2
performed at the bedside, making it especially useful for patients with limited mobility. Additionally, NIRS requires little cooperation from the subjects. There is no known health risk from NIRS. Our results demonstrate that a decreased activation of the visual cortex in patients with optic neuritis can be demonstrated when NIRS is used. We are unaware of any previous reports of NIRS in the field of ophthalmology. Although the sensitivity of this method remains to be studied, NIRS may well be a promising method by which to detect visual
BRIEF REPORTS
355
dysfunction in patients with visual deficits both objectively and noninvasively. REFERENCES
1. Kato T, Kamei A, Takashima S, Ozaki T. Human visual cortical function during photic stimulation monitoring by means of near-infrared spectroscopy. J Cereb Blood Flow Metab 1993;13:516 –520. 2. Meek JH, Elwell CE, Khan MJ, et al. Regional changes in cerebral haemodynamics as a result of a visual stimulus measured by near infrared spectroscopy. Proc R Soc Lond B Biol Sci 1995;261:351–356. 3. Villringer A, Chance B. Non-invasive optical spectroscopy and imaging of human brain function. Trends Neurosci 1997;20:435– 442. 4. Ruben J, Wenzel R, Obrig H, et al. Haemoglobin oxygenation changes during visual stimulation in the occipital cortex. Adv Exp Med Biol 1997;428:181–187. 5. Tamura M, Hoshi Y, Okada F. Localized near-infrared spectroscopy and functional optical imaging of brain activity. Philos Trans R Soc Lond B Biol Sci 1997;352:737–742.
FIGURE 1. Color photograph showing marked fat atrophy and sunken appearance of the right eye. Munson’s sign is elicited in down-gaze.
secondary to chronic and persistent eye-rubbing in a healthy child. (Am J Ophthalmol 2005;139:356-357. © 2005 by Elsevier Inc. All rights reserved.)
K
Unilateral Keratoconus in a Child With Chronic and Persistent Eye Rubbing Alexander S. Ioannidis, MRCOphth, Lynne Speedwell, MCOptom, and Ken K. Nischal, FRCOphth PURPOSE: To report a case of unilateral keratoconus in a 7- year-old female, secondary to chronic persistent eyerubbing in the absence of any systemic condition. DESIGN: Observational case report. METHODS: In the case of this child, no organic cause was found to explain the onset of keratoconus other than persistent eye-rubbing in the affected eye. RESULTS: Nocturnal eye padding was instigated and the condition stabilized. She was reviewed over a 2-year period of follow-up. CONCLUSIONS: Eye-rubbing has been implicated in the pathogenesis of keratoconus. Eye-rubbing is also often a feature of a number of conditions linked to keratoconus such as Down syndrome, atopic keratoconjunctivitis, mental retardation, and Lebers’ congenital amaurosis. There are a number of reports linking eye-rubbing and keratoconus in children, typically in relation to these conditions. However, in this case the keratoconus was Accepted for publication July 22, 2004. From the Department of Ophthalmology, Great Ormond Street Hospital for Children, London, United Kingdom (A.S.I., L.S., K.K.N.); and the Department of Visual Sciences, Institute of Child Health, London, United Kingdom (K.K.N.). Inquiries to Ken K. Nischal, Department of Ophthalmology, Great Ormond Street Hospital, Great Ormond Street, London WC1N3JH United Kingdom; fax: 0114-207-829-8647; e-mail: [email protected]
356
AMERICAN JOURNAL
ERATOCONUS IS CHARACTERIZED BY A NONINFLAM-
matory thinning of the cornea. It is considered a corneal ectasia secondary to stromal thinning1 although some have suggested that it is a type of corneal warpage in the mild to moderate forms of the disease.2 A female child presented with unilateral keratoconus, secondary solely to chronic eye-rubbing. A 7-year-old female was referred to our unit because of a history of apparent enophthalmos and reduced visual acuity in the right eye. She was observed rubbing her right eye persistently since the age of 6 months with no history of itchiness or discomfort in the eye. Systemic examination was normal. Her visual acuity was 6/60 in the right and 6/6 in the left eye unaided. There appeared to be some fat atrophy giving the appearance of a sunken orbit with 1 mm of lid retraction on the right side and a deep upper sulcus. On downgaze, there was evidence of Munson’s sign in the right eye (Figure 1). There was no evidence of Vogts striae or a Fleischer ring. On the Hertel exophthalmometer the corneal apices measured bilaterally at 16 mm. There was no evidence of a papillary or follicular reaction on the tarsal conjunctivae bilaterally. Anterior chambers were deep and quiet, and the intraocular pressures were 13 mmHg in both eyes. Fundi were normal. MRI of the orbits was also normal. Keratoscopy revealed a cone inferolateral to the center of the cornea with thinning (384 ) and a high degree of astigmatism in the right eye. Retinoscopy revealed a clear scissor reflex in the right eye and cycloplegic refraction showed that she had a ⫺3.75 to 7.75 cyl ⫻ 15 error in the right eye. There was no refractive error in the left eye. Nocturnal eye padding was initiated to minimize the eye-rubbing episodes. A genetic screen was performed and was found to be normal. Subsequently, she presented with a central corneal scar in the right eye 4 mm in diameter, OF
OPHTHALMOLOGY
FEBRUARY 2005