Comparison of intraocular pressure measurements with different contact tonometers in young healthy persons

AIM：To analyze the correlation of Goldmann applanation tonometer（GAT）,I-Care tonometer and Tono-Pen tonometer results in young healthy persons,and to investigate the influence of central corneal thickness（CCT）on intraocular pressure（IOP）measurements recorded with these tonometers.·M ETHODS：We conducted a pilot clinical study in 78eyes of 78 subjects aged 22-28 years old（44 women and34 men;mean age 23.8±1.19y）.IOP was measured using GAT,I-Care and Tono-Pen tonometers,followed by measurements of CCT.Statistical analysis was performed using SPSS 20.0.·RESULTS：The mean IOPs and standard deviation（±SD）for GAT,I-Care and Tono-Pen were 15.62±2.281 mm Hg,16.29±2.726 mm Hg and 16.32±2.393 mm Hg,respectively.The mean CCT was 555.15±29.648μm.Clear positive correlations between GAT and I-Care,GAT and TonoPen,and I-Care and Tono-Pen tonometers were found（=0.867,〈0.001;=0.861,〈0.001;=0.915,〈0.001,respectively）.In comparison between devices,BlandAltman analysis showed a significant mean difference（MD）in the measurements by GAT and I-Care of-0.679 mm Hg and by GAT and Tono-Pen of-0.705 mm Hg（〈0.001）,but there was no significant difference between I-Care and Tono-Pe（〉0.05）.Both non-gold standard tonometers were affected by CCT;that is,both I-Care and Tono-Pen tonometer values were significantly higher with higher CCT means（〉555μm;MD=-1.282,〈0.001;MD=-0.949,〈0.001,respectively）compared with GAT.·CONCLUSION：Both I-Care and Tono-Pen tonometers overestimated IOP compared with the GAT values.Either the I-Care or Tono-Pen tonometer could be used instead of GAT because there was no significant difference between their results.Higher CCT values（〉555μm）were associated with overestimated IOP values.

Endothelial parameters in central and peripheral cornea in patients wearing contact lenses

AIM： To measure the parameters of endothelium in the central and peripheral parts of the cornea and evaluate the influence of wearing the hard and soft contact lenses on the mentioned parameters.METHODS： A specular microscope was used to measure the corneal endothelium parameters in both eyes of 139 Caucasians（a total of 278）. All participants were divided into three groups： soft lens wearers, hard lens wearers and a control group. Factors, such as age, smoking, types of lens material, duration of lens wear and lens air permeability were assessed to determine their impact on the morphometric parameters of the endothelium.RESULTS： A lower percentage of hexagon-like cells and higher cell variation than in other groups were determined in hard contact lens wearers. The difference in density of endotheliocytes between the groups was not observed. The measurements of the morphometric parameters in soft contact lens wearers did not depend neither on the duration of lens wear, nor on air permeability. The relation between the patients＇ age and the variation of endothelium parameters was determined in the group of hard contact lens wearers.CONCLUSION： Wearing hard contact lenses provokes pleomorphism and polymegethism of the corneal endothelium, while soft contact lenses do not impact any parameters of the endothelium, most likely due to higher air permeability.

Rabbit models of dry eye disease: comparative analysis

AIM:To report ocular changes in rabbits after the implementation of three different induction methods to create dry eye(DE)conditions and provides evidence of DErelated disease evolution.METHODS:Experimental methods were divided into 3 models.The first model used involved triple injection of complete Freund’s adjuvant,50µL each,also called the meibomian gland dysfunction(MGD)model.In the second model,DE conditions were created by the resection of nictitating membranes(NM),Harderian glands(HG),and main lacrimal glands(LG),also called the LGR model.The third model involved the topical administration of benzalkonium chloride(BAK)0.1%solution.The Schirmer test,ocular surface staining with fluorescein,and tear breakup time tests were implemented before and after excision.After euthanasia,the ocular tissues were dissected.Cornea,conjunctiva,and meibomian glands were treated with periodic acid–Schiff(PAS)staining and haematoxylin–eosin staining.RESULTS:The MGD model triggered inflammation of meibomian glands.It detected changes in the lipid layer of the tear film.The bilateral resection of NM,HG,and LG reduced the watering layer of the tear film.The topical administration of BAK of 0.1%solution impacted the mucosal layer of the tear film.CONCLUSION:Different changes are observed with different DE syndrome models.The composition of the tear film differ depending on which part of the eye is targeted.More studies need to be done to confirm whether an increased thickness of the cornea has any impact on the DE disease.

Green tea——a new perspective of glaucoma prevention

AIM:To determine how green tea and catechins can affect intraocular pressure(IOP)changes.METHODS:Totally 43 young volunteers were included in the study.The experiment was held between noon and 2 p.m.Two extracts—green tea and epigallocatechin gallate(EGCG,400 mg capsules)and placebo(400 mg capsules)were used in the study.Participants were divided into three groups.Green tea extract group(GT group)had 17 subjects,EGCG extract group 17 subjects,control(placebo)group 9 subjects.IOP was measured with the Icare tonometer before and 30 min,1,1.5,2 h after the consumption of each extract and placebo.Results were analyzed using the IBM SPSS program.Statistical confidence level P<0.05.RESULTS:The most significant reduction of IOP from the beginning of the experiment was measured after 2 h in GT group(left 2.18±3.19 mm Hg,P=0.012;right 2.59±1.97 mm Hg,P<0.000)and after 1 h in EGCG extract group(left 2.41±2.98 mm Hg,P<0.004;right 1.94±1.98 mm Hg,P<0.001).In control group no significant changes were measured.CONCLUSION:People who have increased IOP or risk factors for glaucoma development,could benefit from drinking green tea or its concentrated extracts in moderate doses.