Simultaneous recording of multifocal VEP responses to short-wavelength and achromatic stimuli

A paradigm is introduced that allows for simultaneous recording of the pattern-onset multifocal visual evoked potentials (mfVEP) to both short-wavelength (SW) and achromatic (A) stimuli. There were 5 sets of stimulus conditions, each of which is defined by two semi-concurrently presented stimuli, A64/SW (a 64% contrast achromatic stimulus and a short-wavelength stimulus), A64/A8 (64% achromatic/8% achromatic), A0/A8 (0% (gray) achromatic/8% achromatic), A64/A0 and A0/SW. When paired with A64 as part of A64/SW, the SW stimulus yielded mfVEP responses (SWmfVEP) with diminished amplitude in the fovea, consistent with the known sensitivity of the S-cone system. In addition, when A8, which is approximately equal to the L and M cone contribution of the SW stimulus, was recorded alone, the response to A8 was small, but significantly larger than noise. However, when A8 was paired with A64, the response to A8 was reduced to close to noise level, suggesting that the LM cone contribution of the SWmfVEP can be suppressed by A64. When A64 was recorded alone, the response to A64 was about 32% larger than the mfVEP for A64 when paired with the SW. Likewise, the presence of A64 stimulus also reduces the response of SWmfVEP by 35%. Finally, an intense narrow-band yellow background prolonged the latency of SW response for the A0/SW stimulus but not the latency of SW response for the A64/SW stimulus. These results indicate that it is possible to simultaneously record an SWmfVEP with little LM cone contribution along with an achromatic mfVEP.     

Accommodation,convergence and aging

It is generally believed that the ratio of accommodative convergence to accommodation (AC/A ratio) is relatively constant with age. This is based on studies of what is known as the AC/A stimulus ratio in which the denominator is the accommodative stimulus value. However, if the objective accommodative response to each stimulus is used instead in the denominator, then the ratio, called the AC/A response, is not constant but shows an increase beginning just prior to presbyopia. This suggests that greater effort is necessary for a unit of lens accommodation when one gets older or conversely a given effort produces less and less accommodation with age. The disparity between AC/A stimulus and AC/A response is discussed with reference to clinical presbyopia.Supported in part by GRANT #EY00191 of the National Eye Institute.A preliminary report was presented at the New York Academy of Medicine, Ophthalmology Section, May 20, 1968.     

Botox: shaken, not stirred

PURPOSE: To determine whether the effect of botulinum toxin type A is maintained and has the same duration when it is reconstituted vigorously. METHODS: A prospective, double-blinded, randomized study was performed on 7 consecutive patients who underwent botulinum toxin type A injections to the forehead by one oculoplastic surgeon. Half of each patient's forehead was injected with botulinum toxin type A that had been gently reconstituted according to the package insert and the other half of the forehead was injected with botulinum toxin type A that had been reconstituted vigorously. Eyebrow excursion was measured in millimeters before injection, 1 week after injection, and every month after injection up to a total of 6 months. RESULTS: Seven consecutive patients with an average age of 39.9 +/- 2.8 years were evaluated. There was no statistically significant difference in eyebrow excursion between the side of the forehead that had been injected with gently reconstituted botulinum toxin type A and the side that had been injected with vigorously reconstituted botulinum toxin type A at every visit. CONCLUSION: The effect of botulinum toxin type A is maintained and has the same duration when it is reconstituted vigorously compared with when it is reconstituted gently.     

Influence of accommodative and vergence adaptation on binocular motor disorders

Tait described four categories of binocular disorders including convergence excess, convergence insufficiency, divergence excess, and divergence insufficiency. These disorders are defined by the distance where the largest heterophoria occurs (distance or near), and the amplitude of the accommodative vergence ratio (AC/A). Insufficiency corresponds to a low AC/A ratio, whereas excess corresponds to a high AC/A. The magnitude of the AC/A ratio, which may be influenced by the adaptability of the accommodation and vergence systems, has been shown to be reciprocally related to adaptability of accommodation. Likewise, the degree of vergence accommodation has been shown to be related reciprocally to adaptability of vergence to prism. An imbalance of adaptability of accommodation and vergence systems produces abnormal cross-coupling between the two motor systems. When accommodation is more adaptable than vergence, the AC/A ratio is low and the CA/C ratio is high. Conversely, when vergence is more adaptable than accommodation, the AC/A ratio is high and the CA/C ratio is low. A method is reported for temporarily restoring moderate amplitudes of abnormal AC/A and CA/C ratios by reducing excessive adaptation with fatigue. Finally, new clinical procedures for measuring adaptation of accommodation and the CA/C ratio are presented. Taken together with current measures of vergence adaptation and AC/A ratio these procedures will permit a more complete evaluation of mutual interactions between accommodation and vergence in patients diagnosed as having excessive and insufficient vergence.     

A new method of determining the cell density from a corneal specular micrograph

Non-contact specular micrographs of the corneal endothelium are usually only a few cell diameters in width. The oblong shape leads to uncertainties in the determination of cell density by counting the number of cells on an area of known size. A new method, particularly suited for a long and narrow picture, is described. A line with a length corresponding to 1 mm is drawn on a specular micrograph. The number n of cells sectioned by this line is counted. It is demonstrated that the average cell size A may be determined from n by the formula A = 1 404 669/n2 micron2. The relation between A and n is presented in Table 1, which also gives the corresponding cell density expressed by the number of cells per mm2.     

Botox® after Botox® - a new approach to treat diplopia secondary to cosmetic botulinic toxin use: case reports

A new technique for the treatment of diplopia secondary to cosmetic botulinum toxin A use is described. In this interventional case reports, two consecutive patients who developed diplopia after periocular cosmetic use of botulinum toxin A were treated with intramuscular botulinum toxin A injection into the antagonist extraocular muscle. Diplopia resolved in both patients in less than 1 week with no side effects or complications. In conclusion, the injection of intramuscular botulinum toxin A is an encouraging option for treatment of diplopia secondary to botulinum toxin A use for facial lifting.     

Future clinical applicability of optical coherence tomography angiography

Optical coherence tomography angiography (OCT‐A) is an emerging technology that allows for the non‐invasive imaging of the ocular microvasculature. Despite the wealth of observations and numerous research studies illustrating the potential clinical uses of OCT‐A, this technique is currently rarely used in routine clinical settings. In this review, technical and clinical aspects of OCT‐A imaging are discussed, and the future clinical potential of OCT‐A is considered. An understanding of the basic principles and limitations of OCT‐A technology will better inform clinicians of its future potential in the diagnosis and management of ocular diseases.     

Photooxidation of A2-PE, a photoreceptor outer segment fluorophore, and protection by lutein and zeaxanthin

A2-PE is a pigment that forms as a byproduct of the visual cycle, its synthesis from all-trans-retinal and phosphatidylethanolamine occurring in photoreceptor outer segments. A2-PE is deposited in retinal pigment epithelial (RPE) cells secondary to phagocytosis of shed outer segment membrane and it undergoes hydrolysis to generate the RPE lipofuscin fluorophores, A2E, iso-A2E and other minor cis-isomers of A2E. We have demonstrated that A2-PE can initiate photochemical processes that involve the oxidation of A2-PE and that, by analogy with A2E are likely to include the formation of reactive moieties. We also show that potential sources of protection against the photooxidation of A2-PE are the lipid-soluble carotenoids zeaxanthin and lutein (xanthophylls), that constitute the yellow pigment of the macula. Irradiation of A2-PE in the presence of lutein or zeaxanthin suppressed A2-PE photooxidation and in experiments in which we compared the antioxidant capability of zeaxanthin and lutein to alpha-tocopherol, the carotenoids were more potent. Additionally, the effect with zeaxanthin was consistently more robust than with lutein and when alpha-tocopherol was combined with either carotenoid, the outcome was additive. Lutein, zeaxanthin and alpha-tocopherol were all efficient quenchers of singlet oxygen. We have also shown that lutein and zeaxanthin can protect against A2-PE/A2E photooxidation without appreciable consumption of the carotenoid by chemical reaction. This observation contrasts with the pronounced susceptibility of A2E and A2-PE to photooxidation and is of interest since lutein, zeaxanthin, A2E and A2-PE all have conjugated systems of carbon-carbon double bonds terminating in cyclohexenyl end-groups. The structural features responsible for the differences in quenching mechanisms are discussed. It has long been suspected that macular pigment protects the retina both by filtering high-energy blue light and by serving an antioxidant function. Evidence presented here suggests that the photochemical reactions against which lutein and zeaxanthin protect, may include those initiated by the A2-PE. Quantitative HPLC analysis revealed that in eyecups of C57BL/6J and BALB/cByJ mice, levels of A2-PE were several fold greater than the cleavage product, A2E. Taken together, these results may have implications with respect to the involvement of A2-PE formation in mechanisms underlying blue light-induced photoreceptor cell damage and may be significant to retinal degenerative disorders, such as those associated with ABCA4 mutations, wherein there is a propensity for increased A2-PE synthesis.     

计算法和梯度法测量AC/A在不同眼位中的应用比较

目的:讨论分析计算法和梯度法测量调节性集合与调节的比值(AC/A)在不同眼位中的临床应用。方法:收集就诊于眼科门诊的127例近视患者,采用近远距隐斜眼位得到计算法AC/A和近距附加+1.00D得到梯度法AC/A,比较计算法和梯度法AC/A在不同眼位中的差异。结果:计算法AC/A值高于近距+1.00D梯度法AC/A值(P<0.01);对同一种方法在不同眼位组中比较发现,计算法AC/A和梯度法AC/A在不同眼位组中均有差异,内隐斜组AC/A最高,外隐斜组AC/A最低;对同一眼位组中的两种方法比较发现,在内隐斜组和正视组中计算法AC/A高于梯度法(均P<0.01),外隐斜组中两种方法测得AC/A值无差异(P>0.05)。结论:计算法AC/A高于梯度法AC/A,特别是在内隐斜患者和正视患者中使用计算法易得到高AC/A值,造成错误诊断,更推荐使用梯度法。     

The Drug Sensitivity of Cyclosporine A Combined with Antineoplastic Drugs in Retinoblastoma in Vitro

Purpose: To study cyelosporine A inhibition on the fresh retinoblastoma cells in vitro and increasing the drug sensitivity after combined with different antineoplastic drugs. Methods : To study the growth curve of cyelosporine A on 27 samples of primary retinoblastoma cells by MTT assay and to study the change of the drug sensitivity by cyelosporine A combined with seven antineoplastic drugs. Results: The average IC50 of cyelosporine A on the 27 retinoblastoma cells is 67.81μg/ ml and the average inhibitive rate of these samples is 26.1% when cyelosporine A is in the concentration of 2μg/ml. The inhibitive rates all got improved after the seven antineoplastic drugs combined with cyelosporine A and the increasing average inhibitive rate is more than 5. Conclusion: Cyelosporine A can inhibit retinoblastoma cells in vitro and its inhibitive effect is dose dependent. Moreover it can enhance the inhibition of multiple antineoplastic drugs on retinoblastoma cells. Eye Science 2005;21;62-66.     

Retinal vascular development and oxygen-induced retinopathy: a role for adenosine

Adenosine is a ubiquitous molecule that is produced predominantly by catabolism of adenosine triphosphate. Levels of this nucleoside increase dramatically with ischemia and elevated tissue activity. Adenosine levels are high in inner retina during retinal vascular development in postnatal dog. The source appears to be the ectoenzyme 5' nucleotidase, which is prominent at this time in the innermost process of Muller cells. One of the adenosine receptors, A(2A), is present on endothelial cell precursors, angioblasts, and endothelial cells in formed blood vessels in neonatal dog. These observations suggest that adenosine is important in retinal vascular development. Oxygen-induced retinopathy (OIR) is a model for human retinopathy of prematurity (ROP). The initial event in OIR is induced by exposure of the developing retina to high oxygen. Vascular development is halted and over 60% of the retinal vasculature is lost during this stage of the disease in dog, which is called vaso-obliteration. 5' nucleotidase is dramatically reduced during vaso-obliteration, resulting in a sharp decline in adenosine. When animals are returned to room air, the retina is hypoxic because of the lack of blood vessels, oxygen consumption is increased due to neuronal development, and systemic levels of oxygen have returned to normal. At this time, 5' nucleotidase activity and adenosine levels are elevated well beyond normal levels. This stage of OIR is the vasoproliferative stage and A(2A) expression and endothelial cell proliferation are very elevated compared to control animals. Florid preretinal neovascularization forms, which has high levels of adenosine and A(2A) receptors. Therefore, adenosine and its A(2A) receptor appear to be important in canine OIR. This work suggests that adenosine and its receptors may be a therapeutic target in OIR. This hypothesis is supported by recent studies in mouse (Mino et al., Invest. Ophthalmol. Vis. Sci. 42(13) (2001) 3320), which demonstrated that targeting one of the A(2) receptors can inhibit formation of neovascularization in OIR.     

眼前段光学相干断层扫描仪与A超测量中央前房深度的比较

目的前房深度是晶状体性屈光手术和青光眼手术的重要依据之一。为此探讨眼前段光学相干断层扫描仪测量中央前房深度与A型超声测量结果的一致性。方法对白内障30例（45眼）分别使用眼前段光学相干断层扫描仪及A超测量中央前房深度。采用配对t检验对之进行比较;用相关分析方法分析两种仪器测量值之间的相关性;随机选择1眼分别用两种仪器依次重复测量中央前房深度10次,采用变异系数作为评判标准,比较测量的可重复性。结果眼前段光学相干断层扫描仪测量中央前房深度的平均值为（2.63±0.48）mm,A超测量结果为（2.98±0.48）mm;眼前段光学相干断层扫描仪测量的中央前房深度比A超的测量值小（0.35±0.04）mm,眼前段光学相干断层扫描仪与A超测量中央前房深度各值有较好的相关性（r=0.894,P〈0.001）。眼前段光学相干断层扫描仪测量中央前房深度10次变异系数为0.78%,A超测量中央前房深度10次的变异系数为1.49%。结论眼前段光学相干断层扫描仪测量前房深度值比A超测量中央前房深度的各值小;两种仪器检测中央前房深度的测量值相关性较好;眼前段光学相干断层扫描仪测量结果的重复性稍好于A超。临床工作中应把二者结合起来,综合分析。     

低旋设计散光软镜临床配戴结果研究

目的评估低旋（Lo-Torque）设计散光软镜的临床效果。方法103名近视散光自愿者分别配戴A、B镜片各两周。对配戴的临床表现进行客观和主觉评价，采用双盲法。结果①镜片稳定性A镜片旋转范围≤5°为82%，B镜片为52%。②镜片在眼中状态移动度优良者，A镜片为91%，B镜片为95%；中心定位优良者，A镜片为87%，B镜片为77%。③舒适度评价A镜片优良者为85.5%，B镜片为80.2%。结论低旋设计特征的散光软镜更符合人眼的生理特征，可以提高视觉质量，增加配戴舒适度。     

A point mutation (W70A) in the rod PDE-gamma gene desensitizing and delaying murine rod photoreceptors

PURPOSE: To examine the corneal electroretinogram (ERG) of transgenic mice (W70A mice) carrying a point mutation (W70A) in the gene encoding for the gamma-subunit of rod cGMP phosphodiesterase (PDEgamma). METHODS: The ERG of W70A mice was compared with that of normal mice. Cone responses were separated from rod responses by light adaptation, whereas rod sensitivity was assessed by threshold stimulation with dim light. Spectral sensitivity curves of the ERG were obtained using a constant response criterion. RESULTS: The ERG of the W70A mouse has a desensitized, delayed rod b-wave at threshold, and a prolonged rod b-wave at higher flash intensities. The a-wave is absent even at maximal stimulation. The cone ERG of the W70A mouse is indistinguishable from that of normal mice. The spectral sensitivity of the W70A mouse is maximal in the UV spectrum, in contrast to the normal mouse, which is most sensitive in the green region of the spectrum. This supports the interpretation of the results as normal cone and abnormal rod function in the W70A mouse. CONCLUSIONS: The W70A mouse represents new model of stationary nyctalopia that can be recognized by its unusual ERG features.     

Marcus Gunn pupil in a possible case of unilateral retinitis pigmentosa

A possible case of unilateral retinitis pigmentosa (RP) is reviewed. The electrodiagnostic and clinical findings are discussed, with perspective given to alternative diagnoses. A review of the literature is included to show the controversy which clouds a positive diagnosis of unilateral RP. A co-existing Marcus Gunn pupil is defined and discussed in relation to unilateral RP-like processes.     

Two patients with xerophthalmia

BACKGROUND: Xerophthalmia, the eye manifestation of vitamin A deficiency, is one of the main reasons of blindness in developing countries but is rare in industrial countries. PATIENTS: We report on 2 cases of night blindness and conjunctival and corneal xerosis because of hypovitaminosis A. One patient developed vitamin A deficiency due to short bowel syndrome resulting from gastroschisis. The other patient suffered from primary hypovitaminosis A because of malnutrition due to inadequate dietary intake. Electroretinograms were consistent with vitamin A deficiency. Their symptoms quickly improved after vitamin A substitution. CONCLUSION: Although rare in developed countries, ophthalmologists should consider xerophthalmia as differential diagnosis in night blindness and conjunctival and corneal xerosis. Early diagnosis and adequate treatment can prevent permanent visual loss.     

Bilateral corneal ulceration caused by vitamin a deficiency in eosinophilic gastroenteropathy

Purpose: Vitamin A deficiency is a very rare condition in the developed world and can lead to a variety of ocular changes from xerosis and xerophthalmia to corneal ulcer and perforation. The treatment of this devastating disease is simple and inexpensive. It is therefore important to recognize and treat accordingly, especially in the event of ulcers unresponsive to treatment or in the presence of severe malnutrition/malabsorption syndromes. The purpose of this case report is to remind physicians of the potentially devastating effects of vitamin A deficiency on the eyes and to demonstrate outcomes after vitamin A treatment. Methods: Single observational case report. Results: A 29-year-old male with known eosinophilic gastroenteropathy was treated with oral steroids for peripheral ulcerative keratitis. Two weeks after resolution, the patient suffered from peripheral ulcerative keratitis in his other eye, with a self-sealing perforation. Vitamin A deficiency was confirmed and successfully treated, leading to subsequent resolution of signs and symptoms. Conclusions: Vitamin A deficiency can be present in patients with malabsorption and malnutrition syndromes and should be considered as cause of corneal ulceration.     

青少年隐斜视对近视眼发生发展的影响

目的 了解隐斜视与调节性集合/调节比值（AC/A）、调节滞后量之间的关系,探讨隐斜视在近视发生发展中的可能作用。方法 横断面研究。选取近视伴隐斜视青少年62例,检测其屈光度、近距离水平隐斜度及AC/A、调节滞后量。按低、中、高度近视分组,分别对这3组中内隐斜患者与外隐斜患者的AC/A、调节滞后量进行比较,并对隐斜度与AC/A、调节滞后量进行相关性分析。结果 低度近视组内隐斜患者的AC/A、调节滞后量分别为（4.72±0.38）△/D、（-0.50±0.20）D,外隐斜患者分别为（3.4±0.31）△/D、（-0.20±0.10）D;中度近视组,内隐斜患者的AC/A、调节滞后量分别为（4.25±0.55）△/D、（-0.58±0.12）D,外隐斜患者分别为（3.26±0.25）△/D、（-0.30±0.13）D;高度近视组,内隐斜患者的AC/A、调节滞后量分别为（3.63±0.21）△/D、（-0.60±0.10）D,外隐斜患者分别为（2.50±0.29）△/D、（-0.28±0.12）D;3组中内隐斜患者与外隐斜患者的AC/A及调节滞后量差异均有统计学意义。内隐斜度与AC/A呈正相关（r=0.670,P<0.05）,与调节滞后量呈正相关（r=0.430,P<0.05）;外隐斜度与AC/A呈负相关（r=-0.331,P<0.05）,与调节滞后量呈正相关（r=0.423,P<0.05）。结论 近视患者中,内隐斜的AC/A、调节滞后量均大于外隐斜。内隐斜可能比外隐斜更易促进近视发展,隐斜度越大,近视发展越快。较大度数的外隐斜因伴随较大的调节滞后量对近视发生、发展起重要作用。     

A metabolic aspect of transient bilateral external ophthalmoplegia

A case of symmetric external Ophthalmoplegia following hyponatremia and its rapid correction is described. A possible Central midbrain Myelinolysis is proposed. A correlation with Central Pontine Myelinolysis is discussed.     

Congenital ptosis in monozygotic twins

A case of concordance for unilateral congenital ptosis in monozygotic twins is presented. The literature on genetics and congenital ptosis is reviewed. A heritability index is calculated for congenital ptosis, based on all current twin data including the present report. A value for the heritability index of 0.75 is found, suggesting a strong hereditary influence for congenital ptosis. We conclude that twin data strongly support a transmissable genetic defect as contributing to the development of congenital ptosis.