Aproximaciones a la epidemiología de la neuropatía óptica hereditaria de Leber en la comunidad autónoma de Madrid a través de una encuesta a los neuroftalmólogos / Approaches to the epidemiology of NOHL in the region of Madrid: Survey of neuro-ophthalmologists

Objective To estimate the epidemiology of Leber's optic neuropathy (NOHL) in the Region of Madrid. Material and methodsThe neuro-ophthalmologists who work at public hospitals of the CAM were interviewed by telephone. They were asked about the number of patients with NOHL that they had diagnosed during the time that they had been responsible for the neuro-ophthalmology department of that public hospital. The time worked and the population attended by the hospital were used to calculate the number of patient-years in follow-up by each center during the corresponding period. The basic information of each case (date of birth, mutation, and date of visual loss) was registered to avoid duplications. Results Our work estimates a global incidence of 2.34 cases for 10,000,000 inhabitants-year and a prevalence estimated from incidence of one case for each 106,682 inhabitants. This prevalence was very similar in all the studied areas and considerably lower than that reported by other studies. Conclusion This work constitutes the first approach to the epidemiology of this disease in Spain. The prevalence of NOHL in the region of Madrid is probably lower than that reported in the literature in other regions. The prevalence and the incidence were homogeneously low in the 26 studied areas. (AU)

Objetivo Estimar la epidemiología (incidencia y prevalencia) de la neuropatía óptica de Leber (NOHL) en la comunidad autónoma de Madrid (CM). Material y métodosLos neuroftalmólogos que trabajan en los hospitales públicos de la CAM fueron entrevistados telefónicamente. Se les preguntó por el número de pacientes con NOHL que habían diagnosticados durante el tiempo que han sido responsables de la consulta de neuroftalmología de ese hospital público. El tiempo trabajado y la población atendida por el hospital se utilizaron para calcular el número de habitantes-años en seguimiento por cada centro durante el periodo correspondiente y estimar la incidencia en cada área. La prevalencia estimada a partir de la incidencia (PEI) se calculó considerando que un paciente con NOHL vive unos 40 años con la enfermedad. Se registró la información básica de cada caso cuando estaba disponible (sexo, fecha de nacimiento, mutación, fecha de la pérdida visual) para evitar duplicaciones. Resultados Nuestro trabajo estima una incidencia global de 2,34 casos por cada 10.000.000 habitantes-año y una PEI de 1 caso por cada 106.682 habitantes. Esta prevalencia es inferior a la referida por otros estudios. Conclusión Este trabajo constituye la primera aproximación a la epidemiología de esta enfermedad en España. La prevalencia estimada de la NOHL en la CM es probablemente inferior a la reportada en la literatura en otras regiones. La prevalencia y la incidencia fueron homogéneamente bajas en las 26 áreas estudiadas. (AU)

Approaches to the epidemiology of NOHL in the region of Madrid: Survey of neuro-ophthalmologists.

OBJECTIVE: To estimate the epidemiology of Leber's optic neuropathy (NOHL) in the Region of Madrid. MATERIAL AND METHODS: The neuro-ophthalmologists who work at public hospitals of the CAM were interviewed by telephone. They were asked about the number of patients with NOHL that they had diagnosed during the time that they had been responsible for the neuro-ophthalmology department of that public hospital. The time worked and the population attended by the hospital were used to calculate the number of inhabitant-years in follow-up by each center during the corresponding period. The basic information of each case (date of birth, mutation, date of visual loss) was registered to avoid duplications. RESULTS: Our work estimates a global incidence of 2.34 cases for 10,000,000 inhabitants-year and a prevalence estimated from incidence of one case for each 106.682 inhabitants. This prevalence was very similar in all the studied areas and considerably lower than that reported by other studies. CONCLUSION: This work constitutes the first approach to the epidemiology of this disease in Spain. The prevalence of LHON in the region of Madrid, is probably lower than that reported in the literature in other regions. The prevalence and the incidence were homogeneously low in the 26 studied areas.

Mitogen-activated protein kinase inhibitor-associated retinopathy (MEKAR). A clinical case.

Mitogen-activated protein kinase kinase (MEK) inhibitors have significantly improved the prognosis of various types of cancer such as metastatic melanoma. However, their use is usually associated with ocular side effects. A retinopathy associated with these agents (MEKAR) has been described, consisting of the development of neurosensory detachments, generally bilateral and multiple, similar to those that appear in the central serous chorioretinopathy (CSC). Generally, optical coherence tomography allows us to differentiate the two conditions. We present the case of a 55-year-old woman in treatment with a MEK inhibitor, who developed bilateral neurosensory detachments and blurred vision, which resolved with the discontinuance of the treatment due to tumour progression.

Retinopatía asociada a inhibidor de la proteinquinasa de activación mitogénica (MEKAR). A propósito de un caso / Mitogen-activated protein kinase inhibitor-associated retinopathy (MEKAR). A clinical case

Los inhibidores de la proteína quinasa de activación mitogénica (MEK) son fármacos utilizados para el tratamiento de neoplasias tales como el melanoma metastásico. Su introducción ha mejorado el pronóstico de estas enfermedades, pero su uso no está exento de complicaciones oculares. Se ha descrito una retinopatía asociada a estos fármacos (MEKAR) consistente en la aparición de desprendimientos neurosensoriales (DNS), generalmente bilaterales y múltiples similares a los que aparecen en la coriorretinopatía serosa central (CSC). En la mayoría de los casos la tomografía de coherencia óptica es suficiente para diferenciar esta entidad de una CSC. Presentamos el caso de una paciente de 55 años que, en este contexto, desarrolló DNS bilaterales que asociaron disminución de agudeza visual y que se resolvieron cuando se suspendió la terapia por progresión tumoral (AU)

Mitogen-activated protein kinase kinase (MEK) inhibitors have significantly improved the prognosis of various types of cancer such as metastatic melanoma. However, their use is usually associated with ocular side effects. A retinopathy associated with these agents (MEKAR) has been described, consisting of the development of neurosensory detachments, generally bilateral and multiple, similar to those that appear in the central serous chorioretinopathy (CSC). Generally, optical coherence tomography allows us to differentiate the two conditions. We present the case of a 55-year-old woman in treatment with a MEK inhibitor, who developed bilateral neurosensory detachments and blurred vision, which resolved with the discontinuance of the treatment due to tumour progression (AU)

Evaluation of the insertion distance of the medial rectus in consecutive exotropia by means of intraoperative measure and optical coherence tomography.

PURPOSE: To assess the agreement between the measurements of the distance from the medial rectus muscles insertion to the limbus measured by intra-operative spectral-domain optical coherence tomography (SD-OCT) in consecutive exotropia (cXT). METHODS: An analysis was performed on total of 14 medial rectus (MR) muscles of 14 patients who underwent surgery for the treatment of cXT. The limbus-insertion distance of the MR muscles was measured using preoperative SD-OCT and intraoperatively using a calliper. The intraclass correlation coefficient (ICC) and Bland Altman plots were calculated to determine the agreement between the two methods, as well as the correlation. RESULTS: Mean age was 36.3 ± 16.0 years (range 13-60), with 60% being women. Mean preoperative deviation was 38.7 ± 16.9 prismatic dioptres (PD) (range 16-65), being +1.3 ± 6.3 PD (range -12 to +10 PD) after surgery. Intraoperatively the MR insertion was found at 8.7 ± 2.1 mm (range 5.5-12.0) and by OCT at 7.7 ± 1.2 mm (range 5.3-10.0). The ICC showed a moderate to good agreement (0.659; 95% confidence interval: 0.157-0.885; p < 0.001), with a correlation of R = 0.792 (p = 0.011). A better agreement was observed in those MR that were less retro-inserted. CONCLUSIONS: SD-OCT is able to measure the insertion to the limbus distance of the medial rectus muscles that have been previously operated on, showing moderate to good agreement with intraoperative measurements. However, the agreement was poor in muscles with a large retro-insertion.

A variant Nishida's technique for surgical correction of monocular elevation deficiency syndrome.

Monocular elevation deficiency (MED) is characterized by unilateral limitation of supraductions, similar in adduction and abduction, in addition to hypotropia and ptosis. We describe a case of a 62-year-old woman with long-standing left ptosis who was initially operated with a frontal suspension technique. On subsequent examinations, a MED of that eye was found. The passive duction test was positive, so the inferior rectus was recessed. In addition, a modified Nishida technique was performed, consisting of the scleral anchorage of the superior edges of the rectus, medial and lateral, 12mm from the corneal limbus in the superonasal and superotemporal quadrants, respectively. Postoperatively, the left eye presented a minimal hypotropia of 3 PD. This modified technnique used here on the horizontal rectus muscles, turned out to be effective and safe for the correction of MED.

Purtscher-like retinopathy after a stent implant for the treatment of carotid aneurysm.

Purtscher retinopathy is an occlusive microangiopathy associated with traumatic causes and usually causes visual impairment. For non-traumatic origins, it is called Purtscher-like retinopathy (PLR). A 26-year-old man reported loss of vision in his left eye after the implantation of a telescoping stent for the treatment of an intracranial carotid aneurysm. The fundus of the eye showed numerous cotton-wool spots and superficial haemorrhages. The spontaneous evolution was favourable, with almost complete resolution, except for an inferior residual scotoma. The appearance of PLR may be associated with the implantation of an endovascular stent for the treatment of intracranial aneurysms.

Retinopatía de tipo Purtscher tras implante de stent para el tratamiento de aneurisma carotídeo / Purtscher-like retinopathy after a stent implant for the treatment of carotid aneurysm

La retinopatía de Purtscher es una microangiopatía oclusiva asociada a causas traumáticas que suele cursar con disminución visual. Cuando la etiología no es traumática se denomina retinopatía Purtscher-like (RPL). Un varón de 26años refirió pérdida de visión en el ojo izquierdo tras el implante de un stent telescopado para el tratamiento de un aneurisma carotídeo intracraneal. El fondo de ojo mostró numerosos exudados algodonosos y hemorragias superficiales. La evolución espontánea fue favorable, con una resolución casi completa salvo por un escotoma residual inferior. La aparición de RPL se puede asociar al implante de un stent endovascular para el tratamiento de aneurismas intracraneales (Au)

Purtscher retinopathy is an occlusive microangiopathy associated with traumatic causes and usually causes visual impairment. For non-traumatic origins, it is called Purtscher-like retinopathy (PLR). A 26-year-old man reported loss of vision in his left eye after the implantation of a telescoping stent for the treatment of an intracranial carotid aneurysm. The fundus of the eye showed numerous cotton-wool spots and superficial haemorrhages. The spontaneous evolution was favourable, with almost complete resolution, except for an inferior residual scotoma. The appearance of PLR may be associated with the implantation of an endovascular stent for the treatment of intracranial aneurysms (AU)

Orbital apex syndrome secondary to herpes zoster ophthalmicus.

Herpes zoster ophthalmicus usually presents with ocular manifestations, but neurological complications are much more infrequent. An 84-year-old woman with herpes zoster of the left first trigeminal branch developed herpetic keratouveitis in her left eye despite treatment with oral valaciclovir. Seven days later, a progressive and total left ophthalmoplegia appeared, requiring hospital admission and intravenous treatment with acyclovir and corticosteroids. The neuroimaging was suggestive of an orbital apex syndrome. The evolution of the ophthalmoplegia was favourable, with complete resolution at 5 months, but with decreased visual acuity due to the optic nerve involvement.

Síndrome de ápex orbitario por herpes zoster ophthalmicus / Orbital apex syndrome secondary to herpes zoster ophthalmicus

El herpes zoster ophthalmicus suele cursar con manifestaciones oculares, siendo mucho más infrecuentes las complicaciones de tipo neurológico. Una mujer de 84 años con herpes zóster en el dermatomo de la primera rama trigeminal izquierda, desarrolló una queratouveítis herpética en el ojo izquierdo a pesar del tratamiento con valaciclovir oral. A los siete días, además apareció una oftalmoplejia progresiva y total izquierda que requirió ingreso hospitalario y tratamiento intravenoso con aciclovir y corticoides. La neuroimagen fue sugestiva de un síndrome de ápex orbitario. La evolución de la oftalmoplejia fue favorable con resolución completa a los cinco meses de seguimiento, dejando una disminución de la agudeza visual por la afectación del nervio óptico. (AU)

Herpes zoster ophthalmicus usually presents with ocular manifestations, but neurological complications are much more infrequent. An 84-year-old woman with herpes zoster of the left first trigeminal branch developed herpetic keratouveitis in her left eye despite treatment with oral valaciclovir. Seven days later, a progressive and total left ophthalmoplegia appeared, requiring hospital admission and intravenous treatment with acyclovir and corticosteroids. The neuroimaging was suggestive of an orbital apex syndrome. The evolution of the ophthalmoplegia was favourable, with complete resolution at 5 months, but with decreased visual acuity due to the optic nerve involvement. (AU)

Comparison of postural control between strabismic and non-strabismic children. / Comparativa del control postural entre niños estrábicos y no estrábicos.

OBJECTIVE: To compare the postural control of children with strabismus versus non-strabismus children. MATERIAL AND METHODS: Cross-sectional cohort study with a total of 171 children, including 73 children with esotropia, 24 with exotropia, and 74 controls. Postural control was determined using a dynamometric platform in a standing position in various conditions: eyes open and eyes closed, near and gaze fixation, and with and without foam pad. The studied variables were the area, the mean speed, and the lengths in the X and Y axis of the centre of pressure displacement. RESULTS: Children with esotropia and exotropia had significantly higher mean values (speed, lengths of X and Y) compared to controls. In the open-eye, far distance fixation, and on foam pad, as well as under exam conditions; with eyes open, without foam pad, and far distance fixation, the exotropia values were higher than those of endotropia and controls. With eyes closed, there were no differences between the 3 groups under the described examination conditions, but their values were worse compared to their respective ones with eyes open. CONCLUSIONS: The children with strabismus had a worse postural control than the non-strabismus ones. All of the them appeared to be more unstable with eyes closed than with eyes open, which demonstrates that vision plays an important relevant role in postural stability in both strabismus and non-strabismus children.

Evaluación de la distancia al recto medio en la exotropía consecutiva mediante tomografía de coherencia óptica y medida intraoperatoria / Evaluation of the insertion distance of the medial rectus in consecutive exotropia by means of intraoperative measure and optical coherence tomography

Propósito Valorar la concordancia de la medición intraoperatoria de la distancia de la inserción del recto medio (RM) al limbo corneal con la obtenida preoperatoriamente mediante tomografía de coherencia óptica de dominio espectral (SD-OCT) en pacientes con exotropía consecutiva (XTc). Métodos Se analizaron 14RM de 14 pacientes con XTc posquirúrgica que iban a ser reintervenidos. La distancia inserción-limbo fue medida preoperatoriamente mediante SD-OCT y de forma intraoperatoria con compás. Se calculó el coeficiente de correlación intraclase y un análisis de Bland Altman para analizar la concordancia de las medidas, estudiándose además la correlación de las mismas. Resultados La edad media fue 36,3±16,0años (rango 13-60), siendo el 57% mujeres. La desviación ocular media preoperatoria de la XT fue 38,7±16,9 dioptrías prismáticas (DP) (rango 16 a 65), siendo el resultado tras la cirugía de +1,3±6,3 DP (rango –12 a +10 DP). Intraoperatoriamente se halló la inserción del RM a 8,7±2,1mm (rango 5,5-12,0) y con OCT a 7,7±1,2mm (rango 5,3-10,0). El cociente de correlación intraclase mostró una concordancia moderada-buena (0,659; intervalo de confianza al 95%: 0,157-0,885; p<0,001), hallándose una correlación de R=0,792 (p=0,011). Se observó una mayor concordancia en aquellos RM que se hallaban menos retroinsertados. Conclusiones La SD-OCT puede ser una técnica útil para valorar la distancia de la inserción al limbo corneal de los RM previamente retroinsertados, hallándose una concordancia moderada-buena con la medida intraoperatoria. Sin embargo, la concordancia fue baja en músculos muy retroinsertados (AU)

Purpose To assess the agreement between the intraoperative measurements of the distance from the medial rectus muscles insertion to the limbus and preoperative spectral-domain optical coherence tomography (SD-OCT) in consecutive exotropia (cXT). Methods An analysis was performed on total of 14 medial rectus (MR) muscles of 14 patients who underwent surgery for the treatment of cXT. The limbus-insertion distance of the MR muscles was measured using preoperative SD-OCT and intraoperatively using a calliper. The intraclass correlation coefficient (ICC) and Bland Altman plots were calculated to determine the agreement between the two methods, as well as the correlation. Results Mean age was 36.3±16.0 years (range 13-60), with 60% being women. Mean preoperative deviation was 38.7±16.9 prismatic dioptres (PD) (range 16 to 65), being +1.3±6.3 PD (range -12 to +10 PD) after surgery. Intraoperatively the MR insertion was found at 8.7±2.1mm (range 5.5 - 12.0) and by OCT at 7.7±1.2mm (range 5.3 - 10.0). The ICC showed a moderate to good agreement (0.659; 95% confidence interval: 0.157-0.885; P<.001), with a correlation of R=0.792 (P=.011). A better agreement was observed in those MR that were less retro-inserted. Conclusions SD-OCT is able to measure the insertion to the limbus distance of the medial rectus muscles that have been previously operated on, showing moderate to good agreement with intraoperative measurements. However, the agreement was poor in muscles with a large retro-insertion (AU)

Variante de la técnica de Nishida para la corrección quirúrgica del síndrome de déficit monocular de la elevación / A variant Nishida's technique for surgical correction of monocular elevation deficiency syndrome

El síndrome del déficit monocular de la elevación (SDME) se caracteriza por la limitación de las supraducciones de un ojo, tanto en aducción como en abducción, además de hipotropía y ptosis. Se describe el caso de una mujer de 62 años con ptosis izquierda de larga evolución que fue inicialmente intervenida con una técnica suspensión al frontal. En exploraciones posteriores, se le objetivó un SDME de ese ojo. La ducción pasiva fue positiva, por lo que se le realizó una recesión del recto inferior. Además, se le asoció una técnica modificada de Nishida, consistente en el anclaje escleral de los bordes superiores de los rectos, medio y lateral, a 12mm del limbo corneal en los cuadrantes superonasal y superotemporal, respectivamente. Posoperatoriamente el ojo izquierdo presentaba una mínima hipotropía de 3 dioptrías prismáticas. Esta técnica modificada aquí empleada sobre los rectos horizontales resultó ser eficaz y segura para la corrección del SDME (AU)

Monocular elevation deficiency (MED) is characterized by unilateral limitation of supraductions, similar in adduction and abduction, in addition to hypotropia and ptosis. We describe a case of a 62-year-old woman with long-standing left ptosis who was initially operated with a frontal suspension technique. On subsequent examinations, a MED of that eye was found. The passive duction test was positive, so the inferior rectus was recessed. In addition, a modified Nishida technique was performed, consisting of the scleral anchorage of the superior edges of the rectus, medial and lateral, 12mm from the corneal limbus in the superonasal and superotemporal quadrants, respectively. Postoperatively, the left eye presented a minimal hypotropia of 3 PD. This modified technnique used here on the horizontal rectus muscles, turned out to be effective and safe for the correction of MED (AU)

Evaluation of the insertion distance of the medial rectus in consecutive exotropia by means of intraoperative measure and optical coherence tomography. / Evaluación de la distancia al recto medio en la exotropía consecutiva mediante tomografía de coherencia óptica y medida intraoperatoria.

PURPOSE: To assess the agreement between the intraoperative measurements of the distance from the medial rectus muscles insertion to the limbus and preoperative spectral-domain optical coherence tomography (SD-OCT) in consecutive exotropia (cXT). METHODS: An analysis was performed on total of 14 medial rectus (MR) muscles of 14 patients who underwent surgery for the treatment of cXT. The limbus-insertion distance of the MR muscles was measured using preoperative SD-OCT and intraoperatively using a calliper. The intraclass correlation coefficient (ICC) and Bland Altman plots were calculated to determine the agreement between the two methods, as well as the correlation. RESULTS: Mean age was 36.3±16.0 years (range 13-60), with 60% being women. Mean preoperative deviation was 38.7±16.9 prismatic dioptres (PD) (range 16 to 65), being +1.3±6.3 PD (range -12 to +10 PD) after surgery. Intraoperatively the MR insertion was found at 8.7±2.1mm (range 5.5 - 12.0) and by OCT at 7.7±1.2mm (range 5.3 - 10.0). The ICC showed a moderate to good agreement (0.659; 95% confidence interval: 0.157-0.885; P<.001), with a correlation of R=0.792 (P=.011). A better agreement was observed in those MR that were less retro-inserted. CONCLUSIONS: SD-OCT is able to measure the insertion to the limbus distance of the medial rectus muscles that have been previously operated on, showing moderate to good agreement with intraoperative measurements. However, the agreement was poor in muscles with a large retro-insertion.

A variant Nishida's technique for surgical correction of monocular elevation deficiency syndrome. / Variante de la técnica de Nishida para la corrección quirúrgica del síndrome de déficit monocular de la elevación.

Monocular elevation deficiency (MED) is characterized by unilateral limitation of supraductions, similar in adduction and abduction, in addition to hypotropia and ptosis. We describe a case of a 62-year-old woman with long-standing left ptosis who was initially operated with a frontal suspension technique. On subsequent examinations, a MED of that eye was found. The passive duction test was positive, so the inferior rectus was recessed. In addition, a modified Nishida technique was performed, consisting of the scleral anchorage of the superior edges of the rectus, medial and lateral, 12mm from the corneal limbus in the superonasal and superotemporal quadrants, respectively. Postoperatively, the left eye presented a minimal hypotropia of 3 PD. This modified technnique used here on the horizontal rectus muscles, turned out to be effective and safe for the correction of MED.

Recurrent pre-retinal haemorrhages associated with coagulation factor VII deficiency. / Hemorragias prerretinianas de repetición asociadas a déficit del factor VII de la coagulación.

The case concerns a 20 year-old woman with a sudden visual loss in her left eye. In the fundus examination, a focal pre-retinal haemorrhage was observed in the superior temporal vascular branch with accompanying vitreous haemorrhage. There was a favourable spontaneous outcome. Eighteen months later, she presented with a new visual loss in the same eye, showing a sub-hyaloid pre-macular haemorrhage that was satisfactorily drained by hyaloidotomy using a Nd-YAG laser. The patient had also presented with an upper digestive tract haemorrhage and menorrhagia. A haemostasis study was performed that showed a coagulation factor VII deficiency. This is a very uncommon disorder that has not been previously described in association with the appearance of pre-retinal haemorrhages.

Papillitis and neuroretinitis of tuberculous etiology. / Papilitis y neurorretinitis de etiología tuberculosa.

A 57-year-old man with miliary tuberculosis reported visual loss in his right eye, a month after starting a four-drug antituberculous treatment regimen. On exploration, an inferior segmental optic disc edema was objectived and it was attributed to ischemic aetiology. Ethambutol was withdrawn and 60mg of oral prednisone daily were given with a tapering dosage. One and a half months later, he presented a sudden loss of vision in his left eye. In fundoscopy, a papillary edema accompanied by a foveal neurosensory detachment was observed but with no more accompanying uveitic signs. Treatment was intensified with moxifloxacin and corticosteroids were reduced, showing a resolution of the macular detachment but with optic atrophy. Isolated tuberculous involvement of the optic nerve may possible in the context of miliary tuberculosis. In this case, the adopted therapeutic approach to the initial papillitis, which was interpreted as ischemic, could favour the appearance of a neuroretinitis in the fellow eye.

Atypical presentation of Best Disease. / Presentación atípica de la enfermedad de Best.

CLINICAL CASE: A 43-year-old man was treated for reduced visual acuity, initially attributed to strabismic amblyopia. On fundus examination, bilateral neurosensory detachments (NSD) were observed in posterior pole, surrounded by deposits of lipofuscin. His 3-year-old son was also examined and circumscribed NSD was observed with the presence of pseudohypopyon in OD and a fibrosis scar in OS. The Arden ratio were decreased in electrooculography (EOG) in both patients, and genetic studies revealed a single mutation of the BEST1 gene. DISCUSSION: The existence of extensive bilateral NSD may be an unusual form of presentation of Best disease. Family history, EOG, and genetic study supported this diagnosis.

Papillophlebitis in a young male patient with Buerger's disease. / Papiloflebitis en varón joven con enfermedad de Buerger.

CLINICAL CASE: A 27-year-old male with sudden visual loss of OD. He had a past history of heavy smoking, as well as a chronic ischaemia of his left lower limb of one-year onset. This led to a diagnosis of Buerger's disease, which is an inflammatory thrombotic disorder that affects small and medium vessels. The visual acuity (VA) of OD was 0.9, and in the funduscopy a very congestive papilla was observed, along with venous tortuosity, scattered retinal haemorrhages, but without macular oedema. He progressed favourably, with a complete recovery of VA. DISCUSSION: Papillophlebitis may be an ocular complication of Buerger's disease.