Elastic hysteresis in human eyes is an age‐dependent value

Background: The elastic hysteresis phenomenon is observed when cyclic loading is applied to a viscoelastic system. The purpose of this study was to quantitatively evaluate elastic hysteresis in living human eyes against an external force. Design: Prospective case series. Participants: Twenty‐four eyes of 24 normal human subjects (mean age: 41.5 ± 10.6 years) were recruited. Methods: A non‐contact tonometry process was recorded with a high‐speed camera. Central corneal thickness, corneal thickness at 4 mm from the centre, corneal curvature and anterior chamber depth were measured. Intraocular pressure was also measured using Goldmann applanation tonometry and dynamic contour tonometer. Main Outcome Measures: Energy loss due to elastic hysteresis was calculated and graphed. Results: The mean central corneal thickness was 552.5 ± 36.1 µm, corneal curvature was 7.84 ± 0.26 mm and anterior chamber depth was 2.83 ± 0.29 mm. The mean Goldmann applanation tonometry‐intraocular pressure was 14.2 ± 2.7 mmHg and dynamic contour tonometer‐intraocular pressure was 16.3 ± 3.5 mmHg. The mean energy loss due to elastic hysteresis was 3.90 × 10⁻⁶ ± 2.49 × 10⁻⁶ Nm. Energy loss due to elastic hysteresis correlated significantly with age (Pearson correlation coefficient = 0.596, P = 0.0016). There were no significant correlations between energy loss due to elastic hysteresis and other measurements. Conclusion: Energy loss due to elastic hysteresis in the eyes of subjects was found to positively correlate with age, independent of anterior eye structure or intraocular pressure. Therefore, it is believed that the viscosity of the eye increases with age.     

Intermittent reversal of complete ptosis associated with sphenoid wing meningiomas

CASE REPORT: Ptosis secondary to dense oculomotor pareses generally improves over several months, but intermittent elevation of the eyelid has not been reported. The authors describe two patients who demonstrated intermittent involuntary monocular eyelid elevation in an eye with complete ptosis caused by partial resection of sphenoid wing meningioma. Both patients had complete ophthalmoplegia and decreased corneal sensation. The involved eye was ipsilateral to a meningioma that had been debulked 11 to 12 months previously. Although the lids were devoid of volitional movement, each patient could elevate the lid for 10 to 20 seconds by either tickling the eyelashes or rubbing the eyelids. The lids occasionally rose spontaneously and there was no clinical evidence of aberrant regeneration or cyclic spasm. COMMENTS: Although the mechanism of action of this involuntary eyelid elevation is unknown, it is possible that some process of aberrant regeneration activated by sensory stimuli is responsible.     

Bilateral and unilateral mesodermal corneal metaplasia.

We report on 2 infants, one with a bilateral and the other with a unilateral corneal metaplasia. The first case with bilateral corneal metaplasia showed shortening of both upper and lower lids with formation of symblephara. By ultrasonography the right eye presented with microphthalmos, aphakia, and persistent hyaloid, whereas the inner parts of the left eye appeared to be normal. The question remains to be answered whether this is an abortive cryptophthalmos leading to bilateral corneal metaplasia or a primary corneal metaplasia inhibiting the lid growth. No suggestions concerning the aetiology are made. The second case presented with a unilateral corneal metaplasia, normal eye lids, aphakia, and microphthalmos. This aberration was probably caused by an amniotic band, as it is associated with malformation of the nose on the same side. In case 2 the dermoid was excised and a lamellar corneal graft performed. The histology is reported.     

Elastic properties of human lens zonules as a function of age in presbyopes

Purpose. To investigate the elastic properties of human lens zonules as a function of age in presbyopes. Methods. We studied 16 presbyopic human donor eyes (ages 47-97). Anterior eye sections with crystalline lens, zonules, ciliary body, and sclera were stretched radially. The stretching device consisted of a chamber filled with balanced salt solution and eight radial hooks to hold the anterior eye section. Radial stretching was created with a stepper motor connected to a digital outside micrometer for linear displacement and digital balance for force measurement. Three eye globes were used to test our methodology. For 13 eye globes, the spring constant, elastic modulus of the zonular system, and Young's modulus of the zonules were calculated. Results. We found linear dependence for force-elongation and force-strain relationships at all ages. In young presbyopic eyes (ages 47-60), the Young's modulus of the zonules was 340 mN/mm(2), whereas in older eyes (ages 83-97) it was significantly lower at 270 mN/mm(2). However, the correlation coefficient between Young's modulus and age (47-97 years) was not significant with P = 0.063. Conclusions. The zonular system in presbyopic eyes was linear elastic, and the Young's modulus of the zonules decreased 20% from presbyopic age to late presbyopic age. However, there was no significant correlation between Young's modulus and age in presbyopes.     

The synkinesis between antero-posterior eye position and lid fissure width

We have investigated the antero-posterior position of the eye during normal blinking, gentle and hard lid closing and voluntary lid widening with 12 young subjects. Computer- assisted video analysis was used to measure relative eye position. Involuntary blinks were accompanied by retraction of the eye, which was of similar magnitude to the retraction measured witfi lids restrained, while the lids of the contralateral eye gently closed. Eye retraction is accentuated with hard voluntary lid closure, while voluntary lid fissure widening produced slight proptosis of the globe. Preliminary data suggests a small degree of instability of antero-posterior eye position between blinks. Our results are consistent with previous studies of the association between antero-posterior eye position and lid fissure width.     

Comparison of and correlation between anterior and posterior corneal elevation maps in normal eyes and keratoconus-suspect eyes

PURPOSE: To compare the anterior and posterior corneal elevation maps between keratoconus-suspect eyes and normal eyes. SETTING: Rothschild Foundation, AP-HP, University Paris VII, H?pital Bichat Claude Bernard, Paris, France. METHODS: The anterior and posterior corneal surface elevations were analyzed and compared in 60 normal myopic patients and 48 keratoconus-suspect patients. The anterior and posterior best-fit sphere radii, central and thinnest corneal pachymetries, anterior and posterior aconic shape parameters (aconic radius, aconic asphericity, aconic toricity), and anterior and posterior elevation in the 1.0 mm radius zone were analyzed. The correlations between elevation and aconic shape parameters between the anterior and posterior surfaces were compared. RESULTS: The mean central and thinnest pachymetry values were significantly lower in keratoconus-suspect eyes (P<.0001). Compared with normal eyes, keratoconus-suspect eyes had significantly increased anterior toricity (P = .0002) and posterior toricity (P<.0001), more negative asphericity (P = .042), and higher posterior elevation (P<.0001). The correlation between aconic toricity and the anterior and posterior corneal surfaces was better in keratoconus-suspect eyes than in normal eyes. Aconic asphericity and apical curvature were less correlated in keratoconus-suspect eyes than in normal eyes. CONCLUSIONS: The posterior corneal elevation and the corneal thickness values were different in keratoconus-suspect eyes. The correlation between the anterior and posterior corneal aconic shapes was between keratoconus-suspect eyes and normal eyes.     

Expressibility of meibomian secretion. Relation to age, lipid precorneal film, scales, foam, hair and pigmentation

The lower lids of 274 normal subjects have been examined in the slit-lamp for expressibility of secretion from the Meibomian glands. Secretion could be expressed from on an average 10 glands (median 11), dependent on age, decreasing with increasing age (from 14.5 glands at about the age of 20 to 7 glands above the age of 80). The expressibility was seen to be positively correlated to the thickness of the lipid layer of the precorneal film, estimated by the semiquantitative interference method. It was positively correlated to pigmentation and to ordinary greasy scales on the lid margin. The expressibility negatively correlated to retraction of the Meibomian orifices. The expressibility was found not to be correlated to elevated orifices, foam formation in the external part of the eye, cysts in the tarsus, nor with casts round the eyelashes. It is important to distinguish between cylindric casts (Demodex-induced) and ordinary greasy scales on eye lashes and lid margin.     

Mechanical manipulation of the lids and tear break-up time measurements in Hong Kong Chinese

We measured tear break-up time (TBUT) after lid-rubbing in a single masked experiment, and found that TBUT was unaltered. A further single masked experiment in which non-invasive tear break-up Lime (NITBUT) was measured after the lids were raised as if to apply fluorescent also showed no effect of this interference with the lids. An experiment in which fluorescent was applied either with the lid raised or not raised during fluorescein application, again with the experimenter masked with respect to treatment, also produced no significant difference in TBUT. When we measured TBUT with the lid raised so that it was not in contact with the cornea, there was no difference in TBUT for the group between the "lifted" and 'non-lifted' eye; some subjects showed substantially shorter TBUT values, while others showed substantially longer TBUT values. These findings are surprising in view of the concerns expressed in the literature regarding the sensitivity of the tear film to mechanical interference, and suggest that the tear film is more resistant to disruption than has previously been thought.     

The lids influence on corneal shape

BACKGROUND: The lids are in contact to the corneal surface in normal viewing. Refractive surgery, however, is performed with a speculum in place and thus the lids are not in contact with the cornea. PURPOSE: To investigate central corneal shape with and without the lids touching the corneal surface. METHODS: The technique consists of exporting the point cloud of the topography scanner into computer software that recreates the corneal surface. The technique of surface modeling was used to form central corneal elevation height difference maps of four normal eyes with and without lid contact to the corneal surface. RESULTS: Surface modeling demonstrated the trend that the lids influence the corneal shape. CONCLUSION: The lids distort corneal shape.     

Ocular Involvement in Xeroderma Pigmentosum

A 37-year-old, white woman with xeroderma pigmentosum had reduced vision for many years because of primary and secondary corneal epithelial edema and stromal haze. Corneal grafting was required, but was not successful. Numerous primary dermal tumors of various types involving the lids of both eyes had been excised surgically or treated by freezing with liquid nitrogen. Squamous cell carcinomas involving the limbal area of the globe and adjacent tissues were excised from the left eye at age 12, the right eye at age 32, and the left eye (again) at age 36. The right limbal tumor soon recurred and invaded the orbit despite radiation treatment; this required right orbital exenteration. The second left limbal tumor recurred one year later, soon after the recurrence of a left lower lid basal cell carcinoma. Left orbital exenteration was required. Corneal graft failures and recurrent ocular squamous cell carcinoma involving the eye in xeroderma pigmentosum can be difficult management problems.     

Transposed Cheek Flap in Lower Lid Reconstruction: A Retrospective Case Note Review

Purpose: To review the results of a cohort of patients that had a transposed cheek flap as part of the lower lid reconstruction.

Methods: Patients were identified from a database and a retrospective case note review was conducted. 21 patients were identified but one set of notes was not traceable. 21 lids of 20 patients were included. Data included age, sex, laterality, date and details of surgery and follow up as well as details of any complications and additional surgery where required. Data was collected and analysed using Microsoft Excel.

Results: 9 male and 11 female patients were included. Median age was 51. Follow up ranged from 5 to 176 months (median 34). The posterior lamella was reconstructed in 13 patients. Complications included bulky lids and ectropion as well as a few cases of corneal irritation from dermal hairs. 8 cases had no complications. 7 cases required revision—2 for trichiasis, 2 for bulky lids and 3 for ectropion.

Conclusion: The transposed cheek flap is a useful technique in the reconstruction of lower lid lesions involving the lateral canthus. The majority of patients had a good cosmetic result and required no further intervention. The most frequent complications were bulky lids and ectropion.     

正常人中央角膜厚度与Goldmann压平眼压的关系

目的:了解正常人中央角膜厚度(central corneal thickness,CCT)的分布特点并探讨其与压平眼压测量值的关系。方法:采用光学角膜测厚仪及Goldmann压平眼压计检测169名正常人CCT和压平眼压。结果:169名受检者右眼平均CCT为0.547mm(95%可信区间0.443~0.651mm),左眼0.551mm(95%可信区间0.453~0·649)。压平眼压右眼平均15.8mmHg,左眼15.5mmHg。CCT与年龄无相关关系,但与压平眼压测量值显著相关。线性回归分析表明,CCT每增加0.018mm,压平眼压增加1mmHg。结论:CCT变异是眼压测量误差的主要来源。CCT较厚的正常个体可表现"眼压增高"被误诊为高眼压症,而CCT偏薄的原发性开角型青光眼患者则可能因眼压测量"正常"被误诊为正常眼压性青光眼。在诊断青光眼或高眼压症时,特别是在眼压值与其他临床表现不符时,应考虑CCT有无变异。     

Spontaneous eyelid expansion after full thickness eyelid resection and direct closure

BACKGROUND/AIMS: Direct closure of eyelid defects gives excellent functional results but is usually restricted to defects measuring less than a quarter of the eyelid length for fear of distorting the palpebral aperture and compromising lid function. The authors have used direct closure in larger defects. The aim of this study was to establish the effects of direct closure of full thickness eyelid margin defects under tension on the palpebral aperture dimensions. METHODS: A consecutive series of patients who had undergone one eyelid, full thickness lid resection repaired by direct closure were identified and invited to have both eyes photographed. The palpebral apertures of both eyes were measured from the photographs by a masked observer. The amount of eyelid resected was recorded from the operation notes. The unoperated palpebral aperture was used as the control. The result were analysed using a paired samples t test. RESULTS: The photographs of 18 patients were included in the analysis. The mean width of excised full thickness lid tissue was 15 mm (range 7-26 mm). The mean vertical palpebral aperture height was 9.2 (SD 1.4) mm in the operated eye as opposed to 9.3 (SD 1.2) mm in the non-operated eye. The mean horizontal palpebral aperture width was 26.1 (SD 1.9) mm in the operated eye as opposed to 26.4 (SD 1.8) mm in the non-operated eye. There was no statistically significant difference between the operated and unoperated horizontal and vertical palpebral measurements. CONCLUSIONS: Direct closure of large full thickness eyelid defects is possible in selected patients with excellent functional and cosmetic results. Eyelid tissue expansion occurs spontaneously following direct eyelid defect closure under tension, restoring the palpebral aperture dimensions.     

全身麻醉下额肌瓣悬吊治疗小儿单眼重度先天性上睑下垂

目的:观察全身麻醉下额肌瓣悬吊术治疗小儿单眼重度先天性上睑下垂的临床效果和特点。方法:对23例小儿单眼重度先天性上睑下垂行全身麻醉下额肌瓣悬吊术,男13例,女10例,2.5～7(平均4.6)岁,患眼提上睑肌力2～4(平均3.1)mm;术前确定健眼平视前方时上睑缘的位置(在上提患眼睑缘至与对侧眼等高时)。术中根据全身麻醉下眼位略上转的状态及术前健眼上睑缘的位置,将患眼睑缘上提至上角巩缘以下1～3mm。结果:随访1wk～1a,20例(87%)双眼睑缘完全或基本等高(双眼上睑缘高度差在1mm内),3例(13%)欠矫,双眼睑缘高相差约2～3mm。所有病例外观术后均较术前有明显改善或改善,均无严重的睑缘畸形、睑外翻和暴露性角膜炎等并发症,但有6例患儿术后外侧睑缘稍低,与对侧眼略不对称。结论:全身麻醉下额肌瓣悬吊术治疗小儿单眼重度先天性上睑下垂关键在于术前确定健眼上睑缘的位置,并根据术中实际眼位的变化确定上睑缘上提的量。     

Stability of Eyelid Height After Graded Anterior-Approach Lid Lowering for Dysthyroid Upper Lid Retraction

Objective: To investigate the outcome of a modified anterior approach surgical procedure for the correction of primary upper eyelid retraction in thyroid eye disease.

Methods: A retrospective review of 52 consecutive cases (in 32 patients) of anterior-approach graded upper lid lowering for the treatment of primary eyelid retraction, carried out at Moorfields Eye Hospital between 2006–2009 was conducted. Measurements of upper margin-reflex distance (MRD), upper lid skin crease height and skin fold height were taken from clinical records and photographs. A comparison between pre-operative and both early and late post-operative measurements was conducted, with a maximal follow-up of 12 months. Surgery was considered successful when all of the following criteria were met; an upper lid margin covering 0.5–1.5?mm of the superior cornea in the 12 o’clock position, smooth eyelid contour, skin crease height within 6–10?mm or upper lid skin fold within 2–5?mm of the lid margin, symmetry of lid position (difference in MRD of <1?mm between both eyes) and patient satisfaction.

Results: A successful outcome was achieved in 86.5% (45/52) of lids with a single procedure. For the whole group, the mean MRD was 7.0?mm pre-operatively and 3.6?mm at 1 month after surgery. The corresponding values from photographic estimates were 6.5?mm and 3.6?mm, respectively. These values remained stable over the maximum follow-up period of 12 months. Under-correction occurred in 6/52 (11.5%) lids, one of which had persistent lateral flare, whereas over-correction occurred in 1/52 (2%).

Conclusions: The described surgical approach produces reasonably predictable and stable outcome for upper eyelid lowering in patients with thyroid eye disease.     

Fusidic acid prophylaxis before cataract surgery: patient self-administration

In a placebo-controlled, randomised, double-blind clinical trial, the authors evaluated the efficacy of patient-administered 1% fusidic acid viscous eye drops in clearing the commonest organisms causing pseudophakic endophthalmitis ( Staphylococcus epidermidis and aureus ) from the lids and conjunctivae of 79 patients before cataract surgery. The treatment group self-administered fusidic acid viscous eye drops four times daily for seven days before surgery; the placebo group received inert ophthalmic drops. Fellow eyes of both groups remained untreated as a natural control. Lower fornix and lid margin cultures were taken from both eyes before and after treatment. Before treatment, there was no statistical difference in organism counts between the groups. After treatment, eyes receiving fusidic acid were more likely to be free of clinically relevant Staphylococcus spp. than all pre-treatment eyes (for lids, P ≤ 0.001; conjunctivae, P = 0.02). A highly significant ( P <0.001) number of lid margins were rendered 'clinically clean' (i.e., 0–49 organisms/swab) by fusidic acid when compared with untreated eyes. Treatment also effectively ( P <0.05) reduced the numbers of bacteria isolated from conjunctivae. This study indicates that there is a highly significant reduction of Staphylococcus spp. (P≤0.001), non- Staphylococcus spp. (P≤ 0.001) and attainment of sterile eyes ( P≤ 0.001) at operation gained by patient self-administration of 1 % fusidic acid four times daily for seven days before surgery.     

Treatment of ptosis in chronic progressive external ophthalmoplegia.

Seventeen patients with ptosis as a feature of chronic progressive external ophthalmoplegia were managed in accordance with a new protocol. An anterior approach levator advancement was performed on seven patients (13 lids) with more than 4 mm of levator function and a brow suspension procedure on eight patients (14 lids) with minimal levator function, in whom the frontalis muscle was relatively spared. Ptosis props were prescribed for two patients with a very weak orbicularis and poor lid closure. Six patients required long term lubricants, and one developed a postoperative corneal abscess associated with a poor Bell's phenomenon. Satisfactory elevation of the lids was achieved in 16 patients (25 lids).     

The effects of blepharorrhaphy induced depression of corneal cholinergic activity

Unilateral lid closure for 8 or more days had previously been shown to reduce rabbit corneal epithelial choline acetyltransferase (ChAc) activity without affecting lactic dehydrogenase activity or thymidine, uridine, leucine and alanine incorporation rates. In the present study, the reduction in ChAc activity was found to be associated with a similar reduction in acetylcholine (ACh) content, to a mean value of 16 and 17%, respectively, of control eye levels. However, on reopening the lids, ACh levels recovered much more rapidly, achieving a mean value 67% of control values (P > 0·05) in 48 hr while ChAc activity was only 23% of control eye levels at 48 hr and required more than 30 days to fully recover.Unilateral lid closure of 10 days was also associated with a small increase in corneal thickness, 0·46±0·09 mm vs. 0·41±0·04 mm (P < 0·05), and reductions in standing electrical potential, 5·5±7·8 mV vs. 13·2±15·2 mV (P < 0·05), and short circuit current, 2·7±2·6 μA vs. 4·9±3·5 μA (P < 0·05). On re-opening the lids, the short-circuit current recovered within 24 hr, the corneal thickness within 3 days and the resting potential within 4 days. Administration of ACh 10^?4m, pilocarpine 10^?4m, eserine 10^?6m or carbachol 10^?5m to the epithelial side of corneas mounted in chambers immediately after reopening the lids failed to elevate either the standing electrical potentials or short-circuit currents; a causal relationship between cholinergic activity and corneal electrical phenomena could not be demonstrated.     

Posterior corneal surface toricity and total corneal astigmatism.

The influence of posterior corneal surface toricity upon total corneal astigmatism was investigated in 60 young subjects (mean age 22.04 +/- 3.24 years). Both surfaces were found to be flatter horizontally than vertically. Astigmatism arising from the anterior corneal surface was therefore reduced by astigmatism of the opposite sign arising from the posterior surface. Had the toricity of the posterior corneal surface been purely governed by that of the anterior surface this reduction would have amounted to about 5%. However, the posterior surface was found to exhibit additional toricity bringing about a greater reduction of total corneal astigmatism amounting to approximately 14%.     

Treatment of dysthyroid lower lid retraction with autogenous tarsus transplants.

Lower lid retraction is commonly seen in dysthyroid orbitopathy. We have treated 55 lower lids in 38 patients with lower lid retraction by a tarsal transplant from the upper lid to the lower lid. An overall effect of 2-mm improvement +/- 0.7 mm occurred. Eighty-nine percent of the lids achieved the position of the lower lid within 1 mm of the limbus. We think that the upper to lower tarsal transplant offers a technically easy and reasonable solution to moderate lower lid retraction associated with dysthyroid orbitopathy.