泪液渗透压在干眼发病机制中的作用及诊疗进展

干眼是一种以眼表稳态丧失,泪膜不稳定性增加为特征的多因素疾病,伴有眼干涩、异物感、灼烧感、眼红、疼痛、畏光、流泪、眼疲劳、视力下降、分泌物增多、对外界刺激敏感等眼部症状,其病理生理机制主要是泪膜不稳定、泪液渗透压(tear osmolarity, Tosm)升高、眼表炎症和损伤及神经感觉异常。Tosm是维持泪膜稳定性和眼表舒适度的重要因素。Tosm升高可造成干眼患者眼部不适、角膜上皮损伤、杯状细胞丢失及眼部炎症反应,炎症反应可进一步降低泪膜稳定性和增加Tosm,使干眼陷入恶性循环。为了更全面地了解泪液高渗(tear hyperosmolarity, THO)与干眼的关系,本文将从病理生理学方面,重点讨论THO在干眼发病机制、干眼诊断、干眼严重程度分级中的作用,及其针对性治疗。     

Peripapillary retinal nerve fibre layer thickness measurement with SD-OCT in normal and glaucomatous eyes:distribution and correlation with age

AIM:To determine peripapillary retinal fiber layer thickness (RNFL) measured with spectral domain optical coherence tomography (SD-OCT) in normal and glaucomatous eyes in a large sample of exclusively white population and compare results with other similarly constructed studies.METHODS:Average, maximum, minimum and per quadrant RNFL thickness were measured in normal and glaucomatous Greek patients with a scanning laser ophthalmoscope (SLO)/SD-OCT device. The effect of age in normal RNFL thickness was also determined.RESULTS: A total of 278 normal (278 patients) and 67 glaucomatous (67 patients) eyes were included in the study. Average RNFL thickness was 114.8±13.3μm in normal and 92.1±18.5μm in glaucomatous eyes (P<0.001). In normal discs, superior quadrant was the thickest, followed by the inferior, nasal and temporal. Decline of normal RNFL thickness with age was statistically significant for average RNFL thickness (1.92μm per decade of life) and for the superior and inferior quadrants of the disc.CONCLUSION:SD-OCT peripapillary RNFL measurements can be used to distinguish between normal and glaucomatous eyes and establish normative databases, since normal disc measurements differ between different ethnic groups and between different SD-OCT devices.     

The correlation between the tear film lipid layer and dry eye disease

Dry eye, also known as keratoconjunctivitis sicca, can be due either to insufficient tear production or excessive tear evaporation, both resulting in tear hyperosmolarity that leads to symptoms of discomfort and ocular damage. Additionally, the severity of dry eye symptoms appears to be correlated to lipid layer thickness. It is now generally recognized that increased evaporation due to a compromised lipid layer is one of the most common etiologies for hyperosmolarity of the tear film. Thus, therapies targeted at replenishing or stabilizing the lipid layer are key to the treatment of dry eye, either as monotherapy or in conjunction with therapies designed to enhance aqueous production.     

泪液渗透压与干眼严重程度的关联性研究

背景 干眼的发病率逐渐增加,但目前尚无统一的诊断标准.近年的研究提示,泪液渗透压增高可导致眼表不适症状,2007年国际干眼工作小组(DEWS)将泪液渗透压作为伴随症状写入干眼定义中,因此研究泪液渗透压与干眼的关系有重要的临床意义. 目的 依据DEWS干眼严重程度分级标准,分析泪液渗透压与干眼严重程度的相关性.方法 采用描述性研究方法,收集在河南省眼科研究所经传统诊断方法诊断为干眼的患眼54例54眼,询问患者的眼部症状,裂隙灯显微镜下观察眼前节表现,同时行Schirmer试验Ⅰ(SⅠt)、泪膜破裂时间(BUT)试验、泪膜影像学检查、角膜荧光素染色以及泪液渗透压试验,参照和结合DEWS的标准对干眼表现进行评分,将干眼症状评分与泪液渗透压进行相关分析. 结果 男性发病与女性发病的比例为1:2.泪液渗透压与SⅠt、BUT均呈明显负相关(r=-0.456、-0.699,P＜0.01),与泪膜影像学检查值、角膜荧光素染色评分、结膜充血评分、干眼严重程度评分均呈显著正相关(r=0.545、0.686、0.691、0.803,P＜0.01),与年龄、性别相关(β1=141.138,P=0.000;β2=1.845,P=0.049). 结论 泪液渗透压检测可客观地反映干眼的严重程度,结合临床症状和体征可作为干眼严重程度分级的标准.     

干眼症眼表损害炎症机制

干眼症为一种多因素造成泪膜稳定性和眼表功能损害的疾病,易引起眼部不适、视力障碍、泪膜不稳定与眼表的潜在危害,可伴有泪液渗透压升高及眼表炎症反应。炎症是干眼发病中最关键因素,多种免疫细胞和炎症因子参与了干眼症的发生与发展过程。细胞凋亡、神经调节异常、性激素失调等也共同参与了干眼的发病过程。最近尽管在阐述干眼的病理生理和发病机制取得了一定进展,但目前还未形成统一标准。本文将对炎症造成干眼症眼表和泪液功能损害的可能机制进行综述。     

干眼病理损害中的炎症机制

干眼是一种泪液和眼表的多因素性疾病,可引起眼部不适、视觉障碍、泪膜不稳定和眼表损害,并伴有泪膜渗透性升高和眼表炎症。目前研究表明,炎症在干眼的发病和病理损害中起着重要作用。本文从炎症与泪液渗透压、眼表黏蛋白表达、角结膜上皮结构及功能、泪腺及睑板腺结构和功能等方面对炎症造成干眼眼表和泪液功能损害的可能机制进行综述。     

A mass and solute balance model for tear volume and osmolarity in the normal and the dry eye

Tear hyperosmolarity is thought to play a key role in the mechanism of dry eye, a common symptomatic condition accompanied by visual disturbance, tear film instability, inflammation and damage to the ocular surface. We have constructed a model for the mass and solute balance of the tears, with parameter estimation based on extensive data from the literature which permits the influence of tear evaporation, lacrimal flux and blink rate on tear osmolarity to be explored. In particular the nature of compensatory events has been estimated in aqueous-deficient (ADDE) and evaporative (EDE) dry eye.The model reproduces observed osmolarities of the tear meniscus for the healthy eye and predicts a higher concentration in the tear film than meniscus in normal and dry eye states. The differential is small in the normal eye, but is significantly increased in dry eye, especially for the simultaneous presence of high meniscus concentration and low meniscus radius. This may influence the interpretation of osmolarity values obtained from meniscus samples since they need not fully reflect potential damage to the ocular surface caused by tear film hyperosmolarity.Interrogation of the model suggests that increases in blink rate may play a limited role in compensating for a rise in tear osmolarity in ADDE but that an increase in lacrimal flux, together with an increase in blink rate, may delay the development of hyperosmolarity in EDE. Nonetheless, it is predicted that tear osmolarity may rise to much higher levels in EDE than ADDE before the onset of tear film breakup, in the absence of events at the ocular surface which would independently compromise tear film stability. Differences in the predicted responses of the pre-ocular tears in ADDE compared to EDE or hybrid disease to defined conditions suggest that no single, empirically-accessible variable can act as a surrogate for tear film concentration and the potential for ocular surface damage. This emphasises the need to measure and integrate multiple diagnostic indicators to determine outcomes and prognosis. Modelling predictions in addition show that further studies concerning the possibility of a high lacrimal flux phenotype in EDE are likely to be profitable.     

TFOS DEWS II pathophysiology report

The TFOS DEWS II Pathophysiology Subcommittee reviewed the mechanisms involved in the initiation and perpetuation of dry eye disease. Its central mechanism is evaporative water loss leading to hyperosmolar tissue damage. Research in human disease and in animal models has shown that this, either directly or by inducing inflammation, causes a loss of both epithelial and goblet cells. The consequent decrease in surface wettability leads to early tear film breakup and amplifies hyperosmolarity via a Vicious Circle. Pain in dry eye is caused by tear hyperosmolarity, loss of lubrication, inflammatory mediators and neurosensory factors, while visual symptoms arise from tear and ocular surface irregularity. Increased friction targets damage to the lids and ocular surface, resulting in characteristic punctate epithelial keratitis, superior limbic keratoconjunctivitis, filamentary keratitis, lid parallel conjunctival folds, and lid wiper epitheliopathy. Hybrid dry eye disease, with features of both aqueous deficiency and increased evaporation, is common and efforts should be made to determine the relative contribution of each form to the total picture. To this end, practical methods are needed to measure tear evaporation in the clinic, and similarly, methods are needed to measure osmolarity at the tissue level across the ocular surface, to better determine the severity of dry eye. Areas for future research include the role of genetic mechanisms in non-Sjögren syndrome dry eye, the targeting of the terminal duct in meibomian gland disease and the influence of gaze dynamics and the closed eye state on tear stability and ocular surface inflammation.     

Tear film inflammatory cytokine upregulation in contact lens discomfort

PurposeTo investigate the ocular inflammatory response, using clinical and immunological techniques, in people experiencing contact lens (CL) discomfort.MethodsThis study involved 38 adults who were full-time, silicone-hydrogel CL wearers. Participants were categorized into groups based upon a validated CL dry-eye questionnaire (CLDEQ-8) (n = 17 ‘asymptomatic’, CLDEQ-8 score <9; n = 21 ‘symptomatic’, CLDEQ-8 score ≥13). Examinations were performed at two visits (one with, and one without, CL wear), separated by one-week. Testing included: tear osmolarity, ocular redness, tear stability, ocular surface staining, meibography, tear production and tear collection. Tear osmolarity was taken from the inferior-lateral and superior-lateral menisci. The ‘Inferior-Superior Osmotic Difference’, I-SOD, was the absolute osmolarity difference between these menisci. Concentrations of seven cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-gamma, TNF-alpha) were assayed from basal tears using multiplex cytometric bead array.ResultsAt baseline, there was no significant difference in key clinical signs between asymptomatic and symptomatic CL wearers (p > 0.05). The I-SOD was greater in symptomatic than asymptomatic CL wearers (23.1 ± 2.6 versus 11.3 ± 1.4 mOsmol/L, p = 0.001). People experiencing CL discomfort had higher tear IL-17A (122.6 ± 23.7 versus 44.0 ± 10.0 pg/mL, p = 0.02) and reduced tear stability (6.3 ± 1.1 versus 10.4 ± 1.6 s, p = 0.03) after several hours of CL wear. Tear IL-17A levels correlated with both the I-SOD (r = 0.43, p = 0.01) and CLDEQ-8 score (r = 0.40, p = 0.01).ConclusionsCL discomfort occurs in individuals having no clinical dry eye signs, and is associated with higher tear levels of the pro-inflammatory cytokine IL-17A. These findings support an association between the discomfort response and low-grade, ocular surface inflammation.     

应用共聚焦显微镜观察有干眼症状软性角膜接触镜配戴者的角膜神经密度

目的 利用活体共聚焦显微镜分析软性角膜接触镜配戴者干眼症状的出现与角膜上皮下神经密度的相关性.方法 前瞻性临床研究.选择无症状软性角膜接触镜配戴者20例(40眼),有症状软性角膜接触镜配戴者20例(40眼)以及从未配戴软性角膜接触镜者17例(34眼,对照组).利用活体共焦显微镜分别拍摄角膜中央、颞侧及鼻侧上皮下神经密度.比较3组眼表疾病评分问卷(OSDI)得分、角膜荧光素染色评分、泪膜破裂时间(BUT)及Schirmer Ⅰ试验结果.采用单因素方差分析.结果 各组之间BUT( F=9.04,P＜0.01),角膜荧光素评分(F=3.21,P＜0.05)差异具有统计学意义.有症状软性角膜接触镜配戴组Schirmer Ⅰ试验结果较对照组小(P＜0.05).各组间不同方位角膜神经密度比较差异无统计学意义.各组内不同方位角膜神经密度比较,鼻侧与中央、颞侧相比较小,差异均有统计学意义(P＜0.05),中央与颞侧差异无统计学意义.结论 有症状软性角膜接触镜配戴者各项客观的干眼评价指标较未配戴软性角膜接触镜者高,与无症状者基本无差异.软性角膜接触镜配戴者干眼症状的出现不会影响角膜中央、颞侧及鼻侧的神经密度.角膜神经密度中央与颞侧基本无差异,而鼻侧小于中央及颞侧.     

Ocular surface assessment in soft contact lens wearers; the contribution of tear osmolarity among other tests

Purpose:  To determine whether tear osmolarity contributes to the assessment of the ocular surface in soft contact lens (CL) wearers. Methods:  Prospective, case–control series in 44 CL wearers (28 tolerant and 16 intolerant) and 34 healthy subjects. Every patient underwent a thorough ophthalmic examination with a tear osmolarity test (TearLab System), conjunctival impression cytology and meibomian lipid sampling. Symptoms, break‐up time (BUT), tear osmolarity, conjunctival expression of HLA‐DR and meibomian fatty acid composition were evaluated. Results:  Tear osmolarity did not differ between controls and CL wearers (p = 0.23). Flow cytometry results expressed in antibody‐binding capacity (ABC) units and percentage of positive cells revealed a significant difference between the intolerant CL wearer group and the control group (p < 0.0001). Comparisons between tolerant and intolerant CL wearers showed only a significant difference for mean fluorescence levels expressed in ABC units (p < 0.0001). The BUT was significantly shorter in intolerant and tolerant CL wearers subjects than in healthy subjects (p < 0.0001), whereas there was no significant difference in meibomian fatty acid composition (p = 0.99) between the two groups. Conclusion:  Contact lens wear is responsible for ocular surface alterations whose patterns are very similar to those reported in early dry‐eye syndrome. However, tear osmolarity was not modified in these selected CL wearers. The yield of tear osmolarity with TearLab? in assessing ocular surface disorders in CL wearers deserves further investigation.     

The effects of six months of contact lens wear on the tear film, ocular surfaces, and symptoms of presbyopes.

PURPOSE: To assess the tear film, ocular surfaces, and symptoms of ocular discomfort in a presbyopic population before and after contact lens wear. METHODS: A total of 150 presbyopes (49% were previous soft contact lens wearers) participated in a clinical trial in which they wore either monovision (single vision Acuvue lenses) or Acuvue Bifocal contact lenses. Clinical measurements of tear film, biomicroscopy, and corneal sensitivity as well as subjective ratings using the Dry Eye Questionnaire were collected at the initial visit and repeated after 6 months. Comparisons were made between age groups (40 to 51 years and 52 to 71 years) and genders before and after contact lens wear. Associations between objective and subjective tests were sought. RESULTS: After 6 months of contact lens wear, clinical signs had worsened by less than one-half of a grade, and tear break up time (TBUT) worsened by 3 s. Only TBUT was lower for the older age group. Females had less bulbar hyperemia, more sensitive eyes, more lissamine green staining, and lower TBUT and phenol red thread measurements (all p < 0.04). Twenty-eight percent experienced dryness before contact lens wear, but this figure increased to 68% when wearing contact lenses. There were no age differences, but almost twice as many females as males reported dryness. Reporting symptoms of dryness was associated with gender, corneal sensitivity, and type of corneal staining. CONCLUSIONS: These results provide a representation of the ocular surface condition and symptoms of ocular discomfort in the middle-aged population and seem similar to reports of younger populations. Wearing contact lenses seems to influence dry eye symptoms more than age or gender. Therefore, presbyopes should not be excluded from consideration for contact lens fitting.     

New diagnostic methods for imaging the anterior segment of the eye to enable treatment modalities selection

New diagnostic instruments for imaging the anterior segment of the eye have been developed using the corneal topographer, wavefront sensor, and anterior segment optical coherence tomography (OCT). Data obtained from these instruments can be used to choose treatment modalities by providing information that is complementary to slit-lamp examination and visual acuity measurements. Zernike vector analysis was used to evaluate the corneal higher-order aberrations to quantify the effects of the corneal shape on the optical quality of the eye. The analyses showed the optical characteristics of the anterior and posterior surfaces of the cornea in patients with keratoconus or pellucid marginal corneal degeneration. The association between the deterioration of optical quality during rigid gas-permeable contact lens wear in patients with keratoconus and the residual coma due to posterior corneal shape was suggested by the findings made with this method. Zernike vector analyses also revealed the differences in the ocular higher-order aberrations between conventional Laser in situ keratomileusis (LASIK) and custom LASIK. Serial measurements of the ocular higher-order aberrations by a wavefront sensor enabled us to evaluate the effects of tear fluid dynamics on the optical quality of the eye. The findings clarified the characteristics of serial alterations of higher-order aberrations in normal eyes, dry eye with tear deficiency and dry eye with tear evaporation. The effects of internal lubricating agents on the soft contact lenses were also evaluated objectively. In addition, these results suggest that the effects of serial fluctuations in the ocular higher-order aberrations on refractive surgery should be considered. To observe the cornea at the cellular level with anterior segment OCT, a prototype machine of full-field OCT was developed. This made it possible to show epithelial edema in human donor corneas as well as the alterations in the epithelial layer and stromal layer associated with intraocular pressure elevation in ex vivo porcine eyes. An OCT-based corneal topographer was developed using a three-dimensional anterior segment OCT with the swept-source principle. Corneal topographic analyses of the anterior and posterior surfaces either in eyes with keratoconus or following keratoplasty was possible even in where it was difficult for conventional corneal topographers to analyze accurately. Also, OCT-based corneal topographer analyzed the host and donor cornea separately following Descemet stripping automated endothelial keratoplasty by recognizing the host-graft interface. The results from these new diagnostic methods for imaging the anterior segment of eye will be useful for the diagnosis of corneal disorders and the planning of treatment by evaluating the effects of corneal topographic abnormalities and tear fluid dynamics on visual function, by observing the abnormalities of the corneal tissue at the cellular level, and by showing corneal topography in diseased corneas more accurately and non-invasively.     

A new approach for better comprehension of diseases of the ocular surface

The mechanistic view of dry eye disease aims at completing the classic etiological approach that classifies the disease as parallel ocular surface disorders leading to lacrimal film impairment and dry eye. This approach proposes two levels of ocular surface impairment (with standard etiologies, previously validated in the NEI/Industry workshop), which may not be independent diseases but rather risk factors and/or ways to enter a self-stimulated biological process involving the ocular surface. All external disorders proposed in this model, although unlikely to be fully exhaustive, are classical mechanisms considered to be causes of tear film impairment and ocular surface damage, by tear instability and evaporation, tear hyposecretion, or both. These mechanisms, sometimes alone--when severe or becoming chronic or repeatedly present on the ocular surface and when two or more are present--may cause the patient to enter the self-stimulated loop. Tear film instability/imbalance can be considered as the key point of dry eye disease. It will cause local or diffuse hyperosmolarity of the tear film and therefore of superficial epithelial cells of the cornea and/or conjunctiva, stimulating epithelial cells and resident inflammatory cells. Cell damage in the cornea and conjunctiva, by means of apoptosis and direct mechanical and/or osmotic stress, will stimulate the reflex neurosensory arc, in turn stimulating lacrimal gland and neurogenic inflammation, with inflammatory cytokine release, MMP activation, and inflammatory involvement of the conjunctival epithelium. Goblet cell loss is thus directly related to chronic inflammation and surface cell apoptosis subsequent to cell hyperosmolarity and chronic damage, resulting in further tear film instability/imbalance. On the other hand, bacterial changes and an imbalance resulting from specific diseases or from tear film abnormalities may trigger release of endotoxins, lipopolysaccharides, and/or lipase activation, causing eyelid inflammation, meibomian gland dysfunction, and lipidic changes, directly influencing tear film stability and favoring tear evaporation. The lipidic hypothesis therefore participates in the vicious circle as a parallel, independent, or complementary loop. This mechanistic approach proposes a synthetic combination of mechanisms previously validated independently, with two levels of ocular surface impairment, a first level including many possible acute or chronic causes that favor or trigger the imbalance and can be reversible if correctly and specifically managed when possible, and the further involvement of a series of biological cascades centered by tear film imbalance and inflammatory stimulation, finally acting as an independent vicious circle, however the patient entered the loop. Clinically, this approach may explain examples of dry eye syndrome occurring after ocular surgery, contact lens wear, chronic allergy or systemic or topical drugs, and the long-lasting effect even though all causal factors have been removed or have disappeared. This model should be considered as a basis for further reflection on biological mechanisms that could be even more complex but individually constitute potential leads for targeting therapeutic strategies to allow patients to leave the loop even though the triggering factors are still present or can only be attenuated, such as in Sj?gren syndrome or ocular rosacea. It also should be considered a complement to more classic etiological and severity classifications aimed at understanding and classifying the large number of diseases that may cause dry eye disease and better assessing the major impairment it causes on the patient's quality of life.     

Comparison of the effects of first and second generation silicone hydrogel contact lens wear on tear film osmolarity Running title:Tear film osmolarity and silicone hydrogel contact lens wear

AIM: To evaluate the outcomes of pars plana vitrectomy (PPV) without the use of an ocular tamponade in patients having tractional retinal detachment (TRD) secondary to proliferative diabetic retinopathy (PDR).METHODS: It was an interventional study conducted at the Department of Ophthalmology, B.V. Hospital, Bahawalpur, Pakistan, from July 2011 to July 2012. A total of 75 patients (84 eyes) having TRD secondary to PDR were treated by PPV without using an ocular tamponade. All patients included in the study had a tractional retinal detachment secondary to proliferative diabetic retinopathy but didn’t have or develop retinal breaks before or during the study period. The surgical procedure included a PPV combined with the removal of the tractional retinal membranes and the application of endolaser photocoagulation to the retina. The mean follow-up period was 12 months.RESULTS:Successful retinal reattachement was observed in 78 of the operated eyes (92.8%). In these patients, the retina remained attached till the end of the one year follow-up period. Improvement in best corrected visual acuity (BCVA) was seen in 63 eyes (75%). The visual acuity remained unchanged in 9 eyes (10.7%). Mean improvement in BCVA was 2.00+1.24 at baseline to 1.24+1.22 (P<0.05) at the end of the follow-up period.CONCLUSION: In the absence of the retinal breaks, a TRD secondary to PDR can be successfully treated by pars plana vitrectomy without the use of an ocular tamponade.     

Corneal trauma from overnight wear of rigid or soft contact lenses.

To evaluate the mechanical or biochemical insult to the cornea induced by overnight rigid gas permeable (RGP) or soft contact lens (SCL) wear, punctate, stipple staining and corneal blotting were evaluated by biomicroscopy in a group of 23 subjects who participated in a single overnight in-laboratory test session. The soft lens-wearing corneas typically showed greater area of staining along with corneal blotting in comparison to RGP-wearing corneas which showed smaller areas of corneal staining, even in the presence of RGP adherence, and no corneal blotting. We investigated the effect of hypoxia on corneal staining by having subjects wear an RGP lens of Dk = 150 on one eye and a soft lens of Dk = 9 on the fellow eye. Pachometry measurements immediately following eye opening showed an average central corneal swelling of 5 percent for the RGP lens-wearing eye and an average of 11 percent for the SCL-wearing eye. It is likely that the differences in corneal effects of RGP and SCL overnight lens wear are the result of differences in the nature of rigid versus soft contact lens adherence.     

糖尿病患者干眼与眼表异常的相关分析

目的 通过糖尿病患者干眼与眼表异常的相关分析,探讨多种眼表因素异常在糖尿病干眼发病中的作用.方法 收集106例乌鲁木齐市汉族2型糖尿病患者存在的干眼症状及有关的眼表因素（泪液基础分泌、泪膜稳定性、泪液性状、角膜上皮完整性）检查结果,量化后进行单因素及多因素的非条件Logistic回归分析.结果 泪膜稳定性下降（P=0.020,OR=12.268）、泪液基础分泌量减少（P=0.007,OR=5.398）与糖尿病人干眼发生呈显著正相关,具有统计学意义.结论 泪膜稳定性下降、泪液基础分泌量减少在汉族2型糖尿病患者干眼的发病中起一定作用.     

Vitamin D Replacement Improves Tear Osmolarity in Patients with Vitamin D Deficiency

Background: Vitamin D deficiency is a common health problem worldwide. Many parts of the human eye, including the epithelium of the cornea, lens, ciliary body, and retinal pigment epithelium, as well as the corneal endothelium, ganglion cell layer, and retinal photoreceptors, contain vitamin D receptor (VDR). Dry eye is also a common health problem. An adequate tear film is required for maintaining health and function of the eye. Tear hyperosmolarity is considered to be the cause of ocular surface inflammation, symptoms, and tissue damage. It is well-documented that vitamin D has an anti-inflammatory action. We aimed to investigate the effect of vitamin D replacement on tear osmolarity in patients with vitamin D deficiency. Methods: A total of 44 patients (38 females, six males, mean age:43.5 ± 12.8 years) with vitamin D deficiency currently managed by the Endocrinology and Metabolism Department of Diskapi Training and Research Hospital in Turkey were enrolled in the study. Patients were given 50,000 units of 25(OH)D₃ intramuscularly, once weekly, over a period of eight weeks. All of the patients underwent tear function osmolarity (TFO) measurement initially and eight weeks after vitamin D replacement. Demographic, anthropometric, and biochemistry data of patients were recorded. Results: The mean TFO was significantly decreased (313.7 ± 17.3 mOsm/L; 302.7 ± 14.2 mOsm/L, p<0.001) at the end of the second month; 25(OH)D₃ concentrations increased from 8.3 ± 3.5 ng/mL to 68.8 ± 22.3 ng/mL (p<0.001). The mean levels of hsCRP, FPG, P were 2.5 ± 2.5 mg/L, 5.09 ± 0.48 mmol/L, 1.06 ± 0.16 mmol/L initially, and 3.8 ± 5.9 mg/L, 5.11 ± 0.68 mg/dL, 1.09 ± 0.16 mmol/L after vitamin D replacement, respectively (p>0.05). The mean Ca level was 2.37 ± 0.07 mmol/L initially and 2.35 ± 0.07 mmol/L after vitamin D replacement (p<0.05). The change of TFO was negatively correlated with the variation of 25(OH)D₃ before and after replacement in patients with dry eye disease (r=–0.390, p=0.049). Conclusions: As a consequence of the presence of VDR and 1α-hydroxylase in different parts of the eye, vitamin D replacement improves tear hyperosmolarity that is considered to be induced by ocular surface inflammation.     

角膜接触镜长戴研究进展

自1981年长戴型角膜接触镜（EWCL）问世以来,人们逐渐认识到各种EWCL,包括普通型、勤换型与抛弃型软性接触镜（SCL）,以及透气性硬镜（RGP）与硅胶CL,长戴并发症包括接触镜相关性感染性角膜炎（CLAMK）的发病率明显高于日戴。新近推出的高透氧SCL透氧性较普通SCL大大提高。高透氧SCL过夜配戴是否安全？就近年来关于长戴对角膜前泪液膜、角膜与结膜囊微生物丛的影响等方面的研究进展进行了综述。     

Corneal edema in divers wearing hard contact lenses

Polymethylmethacrylate (hard) contact lens-wearing Navy divers involved in hyperbaric research complained of ocular discomfort, halos, specular highlights, and decreased visual acuity during and immediately after the decompression phase of dry chamber dives. These symptoms were related to bubbles in the tear film between the cornea and hard contact lens. The bubbles developed during the decompression phase of the dive and represented the trapping (by the hard contact lens) of nitrogen outgassing from the cornea and precorneal tear film. The bubbles effected nummular patches of corneal epithelial edema persisting up to two hours after diving. Gas trapping and corneal edema were not observed in uncovered corneas or corneas covered with membrane lenses.