A pilot study of the precision of digital intraocular pressure measurement during vitrectomy

AIM:To evaluate the precision of digital intraocular pressure(IOP)measurement in silicone oil(SO)filled eyes during vitrectomy.METHODS:This is a retrospective,single-blind study.Patients who were diagnosed with retinal detachment and scheduled for vitrectomy with SO injection were consecutively enrolled.During the vitrectomy,IOP was digitally measured and then by a rebound tonometer(Icare PRO).The rebound tonometer readings were masked to the surgeons.The digitally measured IOP and that of rebound tonometer were compared,and the inter-methods agreement was assessed.The absolute deviation in IOP values between these two methods(△IOP)was also calculated,and correlations between△IOP and refractive status,lens status and levels of surgeons’experience were analyzed.RESULTS:A total of 131 patients(131 eyes)were recruited,with a mean age of 51.0±16.1 y.There was no significant difference in IOPs between digital measurement and the rebound tonometer(15.6±4.3 vs 15.7±5.1 mm Hg;t=0.406,P=0.686).Intraclass correlation coefficients(ICC)analysis indicated a strong correlation between these two measurements(ICC=0.830,P<0.001).The mean△IOP was 2.0±1.9 mm Hg(range:0-12.8 mm Hg),with 98 eyes(74.8%)had the△IOP within 3 mm Hg.△IOP was found to be negatively correlated with levels of surgeons’experience(r=-0.183;P=0.037),but not with the refractive status or lens status of the patients(both P>0.05).CONCLUSION:For experienced surgeons,the digital IOP measurement may be an acceptable technique for IOP measurement in SO filled eyes during vitrectomy.However,its use by inexperienced surgeons should be taken with caution.

Experimental Tibetan monkey domestication and its application for intraocular pressure measurement

AIM: To train Tibetan monkey (Macaca thibetana) for intraocular pressure (IOP) measurement in conscious state and obtain normal IOP in conscious Tibetan Macaque. METHODS: The training was based on award-conditioned behavior. Food stimulation and human-animal interaction were used in this training. RESULTS: Trained Tibetan monkeys calmly accepted IOP measurement by the TonoVete (R) rebound tonometer without sedation or anesthesia and their IOP values were similar to other primates. CONCLUSION: Human-cultivated Thibetan monkeys are tamable, and can be used for biomedical research such as ophthalmic research without anesthesia.

Impact of corneal parameters on intraocular pressure measurements in different tonometry methods

AIM: To evaluate the impact of central corneal thickness(CCT) and corneal curvature on intraocular pressure(IOP) measurements performed by three different tonometers. METHODS: IOP in 132 healthy eyes of 66 participants was measured using three different tonometry techniques: Goldmann applanation tonometer(GAT), Pascal dynamic contour tonometer(DCT), and ICare rebound tonometer(RT). CCT and corneal curvature were assessed. RESULTS: In healthy eyes, DCT presents significantly higher values of IOP than GAT(17.34±3.69 and 15.27±4.06 mm Hg, P<0.0001). RT measurements are significantly lower than GAT(13.56±4.33 mm Hg, P<0.0001). Compared with GAT, DCT presented on average 2.51 mm Hg higher values in eyes with CCT<600 μm and 0.99 mm Hg higher results in eyes with CCT≥600 μm. The RT results were lower on average by 1.61 and 1.95 mm Hg than those obtained by GAT, respectively. Positive correlations between CCT in eyes with CCT<600 μm were detected for all IOP measurement techniques, whereas a similar relationship was not observed in eyes with thicker corneas. A correlation between IOP values and keratometry in the group with CCT<600 μm was not detected with any of the tonometry methods. In thicker corneas, a positive correlation was found for GAT and mean keratometry values(R=0.369, P=0.005). CONCLUSION: The same method should always be chosen for routine IOP control, and measurements obtained by different methods cannot be compared. All analysed tonometry methods are dependent on CCT;thus, CCT should be taken into consideration for both diagnostics and monitoring.

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.

Tono-pen measurement of intraocular pressure under topical anaesthesia in full term normal newborns

AIM: Tono-pen measurement of intraocular pressure(IOP) under topical anaesthesia in full term normal newborns. ·METHODS: The IOP measurements were taken using Tono-pen XL tonometer under topical anaesthesia in 150 newborns(300 eyes) within 24h after birth,over a period of three months,in a university hospital. Gender,gestation period,mode of delivery and birth weight of newborns were noted from medical records. ·RESULTS: There were 70 males and 80 females. All babies were Malays. The IOP measurements were taken between 12 and 24h after birth. The gestation period of babies ranged between 37 and 41 weeks; 118 babies were delivered by spontaneous vaginal delivery and 32 by caesarian section. The birth weight of babies ranged between 2.1 and 4.3kg. The mean IOP of 300 eyes was 15.99±2.79mmHg(range 8-22). There was no statistically significant difference of mean IOP and gender,laterality of eye,type of delivery,gestation age,or birth weight of newborns. ·CONCLUSION: The IOP in full term normal newborns was 16mmHg. Tono-Pen appears to be ideal instrument for taking IOP in newborns because of its small size and easy handling.

Intraocular pressure measurement over soft contact lens by rebound tonometer: a comparative study

AIM: To evaluate the intraocular pressure(IOP)measurements by Icare rebound tonometer over a contact lens in comparison with Goldmann applanation tonometry(GAT). METHODS: Fifty patients using contact lens were included in this study. One of the eyes of the patients was selected randomly and their IOP were measured by rebound tonometer with and without contact lens(RTCL,RT respectively) and by GAT, as well as their central corneal thickness(CCT) by optical pachymeter. The results of both methods were compared by correlation analysis, general linear method repeated measure and Bland-Altman analysis.RESULTS: Mean IOP values measured by RTCL, RT and GAT were 15.68 ±3.7, 14.50 ±3.4 and 14.16 ±2.8(P 【0.001), respectively. Mean IOP by RTCL was significantly higher than the measurements implemented by RT and GAT(P 【0.001), while there was no difference between the measurements by GAT and RT(P =0.629). There was a good level of positive correlation between GAT and RTCL as well as RT(r =0.786 P 【0.001, r =0.833 P 【0.001, respectively). We have observed that CCT increase did not show any correlation with the differences of the measurements between RTCL and RT(P =0.329), RTCL and GAT(P =0.07) as well as RT and GAT(P =0.189) in linear regression model.CONCLUSION: The average of the measurements over contact lens by rebound tonometer was found to be higher than what was measured by GAT. Although this difference is statistically significant, it may be clinically negligible in the normal population.

Effects of baffie and intraocular pressure on aerosols generated in the noncontact tonometer measurement during COVID-19

AIM: To investigate the effects of baffle and intraocular pressure(IOP) on the aerosols generated in the noncontact tonometer(NCT) measurement and provide recommendations for the standardized use of the NCT during coronavirus disease 2019(COVID-19). METHODS: This clinical trial included 252 subjects(312 eyes) in The Eye Hospital, Wenzhou Medical University from March 7, 2020, to March 28, 2020. Sixty subjects(120 eyes) with normal IOP were divided into two groups. One group used an NCT without a baffle, another group used an NCT with a baffle. Another 192 subjects(192 eyes) were divided into four groups: Group A;(without a baffle+normal IOP), Group A;(without a baffle+high IOP), Group B;(with a baffle+normal IOP) and Group B;(with a baffle+high IOP). Particulate matter(PM) 2.5 and PM10 generated by all subjects were quantified during the NCT measurement. The IOP values were recorded simultaneously. Effects of baffle and IOP on aerosols generated during the NCT measurement were analyzed.RESULTS: In the normal eye group with a baffle, the aerosol density decreased in a wave-like shape near the NCT with the increase in the number of people measured for IOP, demonstrating no cumulative effect. However, in the normal eye group without a baffle, there was a cumulative effect. PM2.5 and PM10 in Group A;were higher than Group A;(both P<0.001). The PM2.5 and PM10 in Group B;were higher than Group B;(P<0.01, P<0.001 respectively). The PM10 of Group B;was lower than Group A;(P<0.01). PM2.5 in Group B;were lower than Group A;(P<0.01). The median of per capita PM2.5 and PM10 in the combined Group A;+A;were 0.80 and 1.10 μg/m;respectively, which were higher than 0.20 and 0.60 μg/m;in the combined Group B;+B;(both P<0.01). The median of per capita PM2.5 and PM10 in the combined Group A;+B;were 0.10 and 0.20 μg/m;respectively, which were lower than 1.30 and 1.70 μg/m;in the combined Group A;+B;(both P<0.001).CONCLUSION: More aerosols could be generated in patients with high IOP. After the NCT is equipped with a baffle, per capita aerosol density generated decreased significantly near the NCT;And with the increase in the number of people measured for IOP, the aerosols gradually dissipated near the NCT, demonstrating no cumulative effect. Therefore, it is suggested that the NCT should be equipped with a baffle, especially for patients with high IOP.

Transpalpebral intraocular pressure measurement by Diaton compared to Goldman applanation tonometer in myopic eyes before and after transepithelial photorefractive keratectomy in Saudi Arabia

AIM:To compare intraocular pressure(IOP)measured via the trans palpebral IOP(tp IOP)method using a Diaton or with a Goldman applanation tonometer(GAT)and study the determinants of IOP difference in eyes undergoing transepithelial photorefractive keratectomy(TPRK)for myopia.METHODS:This cross-sectional validation study was held in 2020 in an eye hospital in Saudi Arabia.IOP was measured by Diaton and GAT before treatment,after one week,and one month of TPRK.It is considered if IOP difference by Diaton and GAT was less than±2 mm Hg acceptable.The IOP difference was tested if correlated to spherical equivalent(SE),central corneal thickness(CCT),age,gender,or tp IOP.RESULTS:Totolly 200 myopic eyes of 100 patients were included in the study.The mean difference of IOP measured by two methods before TPRK,1wk,and 1mo after TPRK were 0.790,-0.790,and-0.920 mm Hg,respectively(P<0.001).Diaton could measure IOP effectively 89.5%eyes before TPRK and 82%and 84%at 1wk and 1mo after TPTK,respectively.At week 1,IOP differences were significantly correlated to baseline CCT(P=0.02)and tp IOP at week 1(P<0.001).One month after TPRK,only tp IOP was significantly correlated to the difference in IOP(P<0.001).CONCLUSION:Diaton is a good screening tool for IOP before TPRK.It helps in monitoring IOP after surgery.Although more practical,it is less efficient than GAT.In eyes with high myopia and low tp IOP before surgery,IOP post-TPRK by Diaton and GAT could differ.

Optimal screening interval for intraocular pressure measurement for Asian glaucoma patients

AIM: To explore the optimal interval of intraocular pressure(IOP) measurement for screening glaucoma in healthy people.METHODS: From January to December 2005, we consecutively enrolled all participants(> 20 years old) attending the Center for Preventive Medicine at St. Luke's International Hospital in Tokyo, Japan, for the annual health check program. The program promoted the early detection of chronic diseases and their risk factors. We excluded people who had glaucoma or a high IOP(≥ 22 mm Hg) at baseline. The annual health check-ups collected all demographic information and medical history with an initial evaluation, including IOP measurement. IOP was measured in both eyes with a full autotonometer TX-F(Canon, Tokyo, Japan). Participants with an IOP ≥ 22 mmH g in either eye were considered to require additional evaluation for glaucoma. We divided the participants into two groups based on age: under 65 years old and over 65 years old. The United States Department of Health and Human Services Cen-ters for Medicare and Medicaid Services guideline was used as a reference. RESULTS: From January 2005 to July 2008, 12 385 participants underwent check-ups each year. The mean ± SD IOP in the higher eye at baseline was 13.4(2.6) in 2005, 13.2(2.7) in 2006, 13.3(2.6), and 12.8(2.6) in 2008. In addition, we analyzed the differences with an analysis of variance(ANOVA), and additional analysis was performed with Bonferroni's correction. The difference between the 4 years was significant(P < 0.01) with ANOVA. Bonferroni analysis revealed significant differences between 2005 and 2006(P < 0.01), 2005 and 2008(P < 0.01), 2006 and 2007(P < 0.01), 2006 and 2008(P < 0.01), and 2007 and 2008(P < 0.01). Only the difference between 2005 and 2007 was not significant(P = 0.1). Logistic regression suggested that only age(P < 0.01) and baseline IOP(P < 0.01) were associated with high IOP; the presence of diabetes, HgbA 1c level, gender, systolic blood pressure, diastolic blood pressure, low-density lipoprotein and family history were non-significant.CONCLUSION: Annual IOP check-ups may be recommended for participants aged ≥ 65 years with baseline IOPs of 17-21 mm Hg. A check-up every 3 years or more may be recommended for patients with IOPs < 17 mmH g.

SEQUENTIAL INTRAOCULAR PRESSURE MEASUREMENTS IN SUSPECTED OPEN-ANGLE GLAUCOMA

Objective To evaluate the variations of intraocular pressure （lOP） in suspected open-angle glaucoma （OAG） patients. Methods The variations of lOP were measured in 216 eyes of suspected OAG patients at 4-hour intervals for 48 h. Based on the results of the serial lOP measurements, optic disc changed and visual field defected, the patients were diagnosed as primary OAG （ POAG ）, normal tension glaucoma （NTG）, ocular hypertension （ OHT） , or physiologic cup （PC）. Results After the serial lOP measurements, 16. 7% of the suspected OAG patients were diagnosed as POAG, 32. 4% as NTG, 24. 5% as OHT, and 26. 4% as PC. The highest percentages of the POAG group had peak lOP at 8 AM （19. 4% ） and their trough lOP at 10 PM （27. 8% ） ; the NTG group had peak lOP at 12 AM （18. 6% ） and their trough lOP at 12 PM （22. 9% ） ; the OHT group had peak lOP at 4 AM （22. 6% ） and their trough lOP at 10 PM （26. 4% ） ; and the PC group had peak lOP at 4 AM （ 21. 1% ） and their trough lOP at 12 PM （ 21. 1% ）. The percentages of peak lOP outside clinic （ 8 AM - 4 PM） in the POAG, NTG, OHT and PC groups were 55. 6%, 50. 0%, 58. 4% and 45. 7%, respectively. The mean magnitude of variance was 5. 1 - 6. 7 mmHg in those suspected OAG patients. There was a strong positive correlation in lOP between both eyes at each time point of measurement and the variation curves of the right and left eyes had parallel profiles in those suspected OAG patients. Conclusion Serial measurement of lOP is still needed, in order not to miss the peak and the trough lOP readings in suspected OAG patients, which helps in better management of glaucoma.

Influence of preoperative astigmatism on corneal biomechanics and accurate intraocular pressure measurement after micro-incision phacoemulsification

AIM: To define the corneal hysteresis(CH), corneal resistance factor(CRF), Goldmann-correlated intraocular pressure(IOPg) and corneal compensated intraocular pressure(IOPcc) prior to and following coaxial micro-incision phacoemulsification in patients with corneal astigmatism. METHODS: Of 97 patients with cataracts were enrolled in the study. Group 1 included patients with corneal astigmatism(K1-K2) values of K1-K2<+1.0 D, and group 2 with values of K1-K2 ≥+1.0 D and ≤+2.25 D. Coaxial micro-incision phacoemulsification of a corneal incision of 2.0 mm with intraocular lens(IOL) implantation was performed. CH, CRF, IOPg, IOPcc, waveform score(WS) were measured preoperatively and one week, one month postoperatively using an Ocular Response Analyzer. Axial length(AXL) was calculated by Tomey Optical Biometer OA 2000.RESULTS: Group 1 consisted of 51 patients with mean corneal astigmatism value of +0.49±0.25 D. Group 2 included 46 patients with astigmatism of +1.43±0.43 D. In group 1, CRF(t=2.68, P<0.05), CH(t=2.64, P<0.05) and WS(t=3.51, P<0.05) were significantly lower one week postoperatively, when compared to the preoperative values. CRF significantly decreased(t=3.61, P<0.05) when measured one month following the surgery. In group 2 CH(t=5.92, P<0.05), and WS(t=3.96, P<0.05) were significantly lowered one week after cataract surgery. Moreover, we observed a significant decrease in IOPg(t=2.24, P<0.05), CRF(t=5.05, P<0.05) and CH(t=2.31, P<0.05) one month after phacoemulsification. There was no statistically significant(t=-0.83, P=0.41) difference in AXL between study groups.CONCLUSION: CRF, CH and IOPg are reduced in patients with preoperative corneal astigmatism equal or higher than +1.0 D and lower than +2.25 D. Hence, bias of IOPg measurement in these patients may cause underestimation of the real IOP both before and after cataract surgery. The measurement of IOPcc allows the precise assessment of IOP pre-and postoperatively, independently on corneal astigmatism, CH and CRF values.

The Influence of Central Corneal Thickness and Corneal Curvature and Axial Length on the Measurement of Intraocular Pressure

Purpose: To examine the influence of central corneal thickness (CCT), corneal curvature (CC), and axial length (AL) on intraocular pressure (IOP).Methods: Eighty-one clinically normal eyes were included in our study. The IOP, CCT, CC, AL were measured using a Goldmann applanation tonometer, optical pachymeter, keratometer and A-scan ultrasound biometer respectively in all subjects.Results: A highly significant positive correlation was identified between IOP and CCT. Linear regression analysis suggests that an increase in CCT of 0. 010 mm is associated with a 4. 946 mmHg increment in IOP. No significant positive correlation was identified between IOP and CC. P values are 0. 724 and 0.414 respectively for vertical and horizontal readings. A paradoxically reversed correlation was present between IOP and axial length.Conclusion: Corneal thickness is a very important confounding factor in the measurement of intraocular pressure, which warrants further attention in our clinical practice.

Modeling and Simulation of Human Cornea for the Measurement of Intraocular Pressure (IOP) through Eyelid

This article describes a study based on the use of an instrumented form of applanation and indentation tonometry through eyelid.The methods and devices which are available for the measurement of intraocular pressure(IOP)have their own limitations.These cause discomfort to the patients during IOP measurement.Also these methods,used to measure IOP over cornea,need anesthesia.In the present work,an attempt is made to develop a device for the measurement of IOP through eyelid which eliminates the need of anesthesia and enhance the patient’s comfort and convenience of the clinician.To represent the results of proposed technique,the human eye modeled with cornea,sclera and also with the eyelid,is used.Furthermore,simulation results of stress values for the range of IOP i.e.5-40 mm of Hg are presented and discussed comparatively with eyelid and without eyelid i.e.directly‘on cornea’methods.

Casein kinase-2 inhibition promotes retinal ganglion cell survival after acute intraocular pressure elevation

Intraocular pressure elevation can induce retinal ganglion cell death and is a clinically reversible risk factor for glaucoma,the leading cause of irreversible blindness.We previously demonstrated that casein kinase-2 inhibition can promote retinal ganglion cell survival and axonal regeneration in rats after optic nerve injury.To investigate the underlying mechanism,in the current study we increased the intraocular pressure of adult rats to 75 mmHg for 2 hours and then administered a casein kinase-2 inhibitor(4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole)by intravitreal injection.We found that intravitreal injection of 4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole promoted retinal ganglion cell survival and reduced the number of infiltrating macrophages.Transcriptomic analysis showed that the mitogen activated protein kinase signaling pathway was involved in the response to intraocular pressure elevation but was not modulated by the casein kinase-2 inhibitors.Furthermore,casein kinase-2 inhibition downregulated the expression of genes(Cck,Htrsa,Nef1,Htrlb,Prph,Chat,Slc18a3,Slc5a7,Scn1b,Crybb2,Tsga10ip,and Vstm21)involved in intraocular pressure elevation.Our data indicate that inhibition of casein kinase-2 can enhance retinal ganglion cell survival in rats after acute intraocular pressure elevation via macrophage inactivation.

Background diseases and the number of previous intravitreal aflibercept injections on immediate intraocular pressure increase and vitreous reflux rate in phakic eyes

●AIM:To evaluate the effect of background diseases and number of previous intravitreal aflibercept injections(IVAIs)on immediate intraocular pressure(IOP)increase and vitreous reflux(VR)rate and to evaluate the correlation of both age and axial length with immediate IOP increase and VR rate.●METHODS:This study included 105 patients with cystoid macular edema secondary to retinal vein occlusion,35 patients with diabetic macular edema,69 patients with neovascular age-related macular degeneration(nAMD),and 12 patients with myopic choroidal neovascularization,which underwent first-time IVAI.The correlation of immediate IOP increase and VR rates with the four background diseases was investigated.Moreover,the correlation of age with immediate IOP increase and VR rate as well as correlation of axial length with immediate IOP increase and VR rate were evaluated.Further,54 patients with nAMD were treated with IVAI>10 times(multiple IVAIs).Moreover,the correlation of immediate IOP increase and VR rates with first-time and multiple IVAIs in nAMD was determined.●RESULTS:The immediate IOP increase(P=0.16)and VR rates(P=0.50)were almost similar among the four background diseases.The immediate postinjection IOP and age,VR rate and age,immediate postinjection IOP and axial length,or VR rate and axial length were not correlated in the four background diseases.The immediate IOP increase(P=0.66)and VR rates(P=0.28)did not significantly differ between first-time and multiple IVAIs in nAMD.●CONCLUSION:Background diseases and number of previous IVAIs have no effect on immediate IOP increase and VR rate.Further,age and axial length have no correlation on immediate IOP increase and VR rate.

Corneal and intraocular pressure changes associated to the circadian rhythms:a narrative review

AIM:To synthesize the current body of research regarding the diurnal variations in intraocular pressure(IOP)and corneal biomechanical and morphological parameters,highlighting their significance in various eye conditions.METHODS:A comprehensive review of studies on the diurnal variations of IOP and corneal parameters was conducted.Tonometry findings from various studies were assessed,including the Goldmann applanation tonometry(GAT)and non-contact tonometers.Data on the variations in central corneal thickness(CCT),corneal curvature,and corneal biomechanics measured by the Ocular Response Analyzer system across different population groups was extracted and analyzed.RESULTS:In both healthy subjects and those with Fuchs dystrophy,IOP and CCT demonstrate marked diurnal declines.GAT remains the gold standard for tonometry,with the highest reliability.However,its measurements are influenced by CCT.Keratoconus patients and those with pseudoexfoliation showed significant diurnal variations in IOP.The biomechanical parameters,especially corneal hysteresis(CH)and the corneal resistance factor(CRF),largely remain stable throughout the day for most of eye conditions,with some exceptions.Notably,the corneal morphology diurnal variation,particularly curvature,yielded mixed conclusions across studies.CONCLUSION:Circadian rhythms significantly influence various corneal parameters,most notably IOP and CCT.Further studies should emphasize standardized approaches larger sample sizes,and delve deeper into less-explored areas,such as the effects of orthokeratology lenses on diurnal biomechanical shifts.

NMI,POLR3G and APIP are the key molecules connecting glaucoma with high intraocular pressure:a clue for early diagnostic biomarker candidates

AIM:To understand the molecular connectivity between the intraocular pressure(IOP)and glaucoma which will provide possible clues for biomarker candidates.METHODS:The current study uncovers the important genes connecting IOP with the core functional modules of glaucoma.An integrated analysis was performed using glaucoma and IOP microarray datasets to screen for differentially expressed genes(DEGs)in both conditions.To the selected DEGs,the protein interaction network was constructed and dissected to determine the core functional clusters of glaucoma.For the clusters,the connectivity of IOP DEGs was determined.Further,enrichment analyses were performed to assess the functional annotation and potential pathways of the crucial clusters.RESULTS:The gene expression analysis of glaucoma and IOP with normal control showed that 408 DEGs(277 glaucoma and 131 IOP genes)were discovered from two GEO datasets.The 290 DEGs of glaucoma were extended to form a network containing 1495 proteins with 9462 edges.Using ClusterONE,the network was dissected to have 12 clusters.Among them,three clusters were linked with three IOP DEGs[N-Myc and STAT Interactor(NMI),POLR3G(RNA Polymerase Ⅲ Subunit G),and APAF1-interacting protein(APIP)].In the clusters,ontology analysis revealed that RNA processing and transport,p53 class mediators resulting in cell cycle arrest,cellular response to cytokine stimulus,regulation of phosphorylation,regulation of type Ⅰ interferon production,DNA deamination,and cellular response to hypoxia were significantly enriched to be implicated in the development of glaucoma.Finally,NMI,POLR3G,and APIP may have roles that were noticed altered in glaucoma and IOP conditions.CONCLUSION:Our findings could help to discover new potential biomarkers,elucidate the underlying pathophysiology,and identify new therapeutic targets for glaucoma.

Intraocular pressure before and after capsulorhexis using two viscoelastic substances and two surgical approaches in enucleated porcine eyes

AIM:To investigate the influence of ophthalmic viscoelastic devices(OVDs)and different surgical approaches on the intraocular pressure(IOP)before and after creation of the curvilinear circular capsulorhexis(CCC)as a measure for anterior chamber stability during this maneuver.METHODS:Prospective experimental WetLab study carried out on enucleated porcine eyes.IOP was measured before and after CCC with the iCare Rebound tonometer(iCare ic200;iCare Finland Oy,Vantaa,Finland).The OVDs used were a cohesive one[Z-Hyalin,Carl Zeiss Meditec AG,Germany;hyaluronic acid(HA)]and a dispersive[Z-Celcoat,Carl Zeiss Meditec AG,Germany;hydroxy propylmethylcellulosis(HPMC)].The CCC was created using Utrata forceps or 23 g microforceps in different combinations with the OVDs.RESULTS:Using the Utrata forceps the IOP dropped from 63.65±6.44 to 11.25±3.63 mm Hg during the CCC.The use of different OVDs made no difference.Using the 23 g microforceps the IOP dropped from 65.35±8.15 to 36.55±6.09 mm Hg.The difference between IOP drop using either Utrata forceps or 23 g microforceps was highly significant regardless of the OVD used.CONCLUSION:Using the sideport for the creation of the capsulorhexis leads to a lesser drop in IOP during this maneuver compared to the main incision in enucleated porcine eyes.The use of different OVD has no significant influence on IOP drop.

Short-term fluctuation of intraocular pressure and influencing factors following intravitreal injection in patients with retinal vascular diseases

AIM:To investigate the patterns of short-term intraocular pressure(IOP)fluctuations and identify the contributing factors following intravitreal injection in patients with retinal vascular diseases.METHODS:Totally 81 patients were enrolled in this case control study.Eyes were categorized into 7 groups,including age-related macular degeneration(AMD),polypoidal choroidal vasculopathy(PCV),idiopathic choroidal neovascularization(CNV),proliferative diabetic retinopathy(PDR),diabetic macular edema(DME),macular edema secondary to branch(BVOME)and central(CVOME)retinal vein occlusion.IOP was measured in all patients using rebound tonometer at 7 preset time points perioperatively.Additionally,based on the administered medication,the eyes were classified into three treatment groups,including dexamethasone intravitreal implant(IVO),intravitreal conbercept(IVC),and intravitreal ranibizumab(IVR).To compare IOP values at various time points across groups,we employed one-way ANOVA,independent sample t-test or χ^(2) test and multivariate logistic regression analysis.RESULTS:Peak IOP values across all groups were observed at 40s,and 5min after intravitreal injection.Statistical differences in IOP were detected at the 5min among the 7 indication groups(F=2.50,P=0.029).When examing the impact of medications,the IVO group exhibited lower average IOP values at both 40s and 5min compared to the IVC and IVR groups(P<0.001;P=0.007).The IOP values at 40s and 5min were significantly higher in BVOME and CVOME group compared to non-retinal vein occlusionsecondary macular edema(RVOME)group(P<0.001).Multivariate logistic regression analysis further confirmed that IOP measurement at 40s was significantly higher in CVOME group than in non-RVOME group(OR=1.64,95%CI:1.09-2.47;P=0.018).CONCLUSION:Needle size plays a crucial role in the transient changes of IOP following intravitreal injection.Before administering intravitreal injection to patients with central retinal vein occlusion,it is essential to exclude any underlysing causes of increased IOP.

Intraocular pressure and gonioscopic findings in primary angle-closure disease in India—a big data study

AIM:To describe the gonioscopic profile and intraocular pressure(IOP)in primary angle-closure(PAC)disease in patients presenting to a tertiary eye care network in India.METHODS:A cross-sectional hospital-based study that included 31484 new patients presenting between 2011 and 2021.Patients with a clinical diagnosis of PAC/suspect/glaucoma were included.The data was collected from an electronic medical record system.RESULTS:PAC glaucoma(PACG)(47.55%)was the most common diagnosis followed by PAC(39.49%)and PAC suspect(PACS;12.96%).Female preponderance(54.6%)was noted with higher mean age at presentation among males(P<0.0001).PACS and PAC showed the highest prevalence in 6th decade but PACG was higher at 7th decade.The probability of angle opening was 95.93%,90.32%and 63.36%in PACS,PAC and PACG eyes respectively post peripheral iridotomy(PI).Plateau iris syndrome(PIS)was noted in 252 eyes and all showed post dilated rise of IOP.A post dilated IOP rise was also noted with 8.86%,33.95%and 57.19%eyes with PACS,PAC and PACG respectively with IOP rise between 6-8 mm Hg across the disease spectrum.CONCLUSION:The superior quadrant is the narrowest angle and difficult to open with indentation and post PI.The probability of angle opening is less in PIS especially the complete variety along with post dilated IOP rise.The post dilated IOP rise in angle closure eyes warrants a careful dilatation,especially with PIS.