Analysis of changes in crystalline lens thickness and its refractive power after laser in situ keratomileusis

AIM: To evaluate changes in the anterior chamber depth (ACD), crystalline lens thickness (LT) and its refractive power after laser in situ keratomileusis (LASIK). METHODS: In all cases, the preoperative and postoperative central ACD which were measured with Pentacam, Orbscan, IOL-Master and A-scan ultrasonography, central corneal true net power which was measured with the Pentacam, Orbscan and IOL-Master, axial length (AL) which was measured with IOL-Master and LT which was measured with the A-scan ultrasonography were compared using the paired sample t test. Ocular refractive errors and lens refractive power at corneal plane were calculated and their correlations were also evaluated before and after LASIK. RESULTS: At 1 week after LASIK, LT and crystalline lens refractive power at corneal plane (Dlens) which were associated with the IOL-Master and Pentacam increased significantly (P <= 0.005), ACD decreased significantly (P <= 0.001), but no significant increase was observed in the Diens which was associated with the Orbscan(P=0.261). Significant correlations between the changes in the ocular refractive errors and Diens which were associated with the Pentacam were observed at 1 week and 6 months after LASIK (P = 0.028; P=0.001). CONCLUSION: LT increased significantly after LASIK, and this might partially lead to ACD decrease, Diens increase and a small quantity of myopic regression.

Lens thickness assessment : anterior segment optical coherence tomography versus A-scan ultrasonography

AIMTo assess lens thickness measurements with anterior segment-optical coherence tomography (AS-OCT) in comparison with A-scan ultrasonography (A-scan US).METHODSThere were 218 adult subjects (218 eyes) aged 59.2&#x000b1;9.2y enrolled in this prospective cross-sectional study. Forty-three eyes had open angles and 175 eyes had narrow angles. Routine ophthalmic exam was performed and nuclear opacity was graded using the Lens Opacities Classification System III (LOCS III). Lens thickness was measured by AS-OCT (Visante OCT, Carl Zeiss Meditec, Dublin, CA, USA). The highest quality image was selected for each eye and lens thickness was calculated using ImageJ software. Lens thickness was also measured by A-scan US.RESULTSInterclass correlations showed a value of 99.7% for intra-visit measurements and 95.3% for inter-visit measurements. The mean lens thickness measured by AS-OCT was not significantly different from that of A-scan US (4.861&#x000b1;0.404 vs 4.866&#x000b1;0.351 mm, P=0.74). Lens thickness values obtained from the two instruments were highly correlated overall (Pearson correlation coefficient=0.81, P&#x0003c;0.001), and in all LOCS III specific subgroups except in grade 5 of nuclear opacity. Bland-Altman analysis revealed a 95% limit of agreement from -0.45 to 0.46 mm. Lens thickness difference between the two instruments became smaller as the lens thickness increased and AS-OCT yielded smaller values than A-scan US in thicker lens (&#x003b2;=-0.29, P&#x0003c;0.001)CONCLUSIONAS-OCT-derived lens thickness measurement is valid and comparable to the results obtained by A-scan US. It can be used as a reliable noncontact method for measuring lens thickness in adults with or without significant cataract.

Associations of lens thickness and axial length with outcomes of laser peripheral iridotomy

AIM:To investigate the association of axial length(AL),lens thickness(LT),and lens vault(LV)with postoperative anterior chamber angle metrics after laser peripheral iridotomy(LPI).METHODS:Prospective observational study of 69 patients(97 eyes)were diagnosed as primary angle-closure suspect(PACS),primary angle closure(PAC)or primary angle-closure glaucoma(PACG).AL,LT,anterior central chamber depth(ACD),angle opening distance(AOD),trabecular iris angle(TIA),and angle recess area(ARA)were measured before and 1 wk after LPI.The association between AL,LT,LV with ACD,AOD,TIA,ARA were analyzed by comparing the differences between preoperative and postoperative measurements for anterior segment biometric parameters.RESULTS:ACD,AOD,TIA,and ARA were significantly increased after LPI(all P<0.05).Greater LT was significantly associated with greater postoperative increases in ACD,AOD,TIA,and ARA(all P<0.05).AL was not significantly associated with changes of anterior segment biometric parameters.Greater LV was significantly associated with greater postoperative increases in ACD,AOD,and TIA(all P<0.05),but was not significantly associated with changes of ARA.CONCLUSION:Greater baseline LT and LV measurements are associated with greater increases in anterior segment biometric parameters after laser peripheral iridotomy.AL are not associated with the change of anterior segment biometric parameters.

Age-related changes of lens thickness and density in different age phases

AIM: To explore the changes in lens thickness and density with age.METHODS: A Chinese population-based retrospective study was performed. A total of 497 individuals(490 right eyes and 495 left eyes), ranging from 3 to 69 years old were included. Lens images obtained from IOL Master 700 were used to measure lens thickness and density. Piecewise regression model was chosen to illustrate the relationship of lens thickness and density with age.RESULTS: The proportion of people aged 3-18, 19-40, over 40 was 38.6%, 50.9% and 10.5% respectively. The whole lens thickness decreased with age during the first 7 years of life, kept stable from 8 to 16 years old, and then increased at the rate of about 27 μm per year. The thickness of the lens cortex and nucleus tended to decrease first and then increase with age, which was dependent on age stages. The whole lens density also decreased with age until 7 years old. The increasing rate of lens density was different in different age groups. The whole lens density increased rapidly from 7 to 22 years old and slowed down after 22 years old. Similarly, the changing tendency of lens cortical and nuclear density differed in different age phases. CONCLUSION: Both lens thickness and density are significantly associated with age, whereas they do not change linearly with age. Moreover, it is necessary to increase the population over 40 years old and conduct further research.

Ultrasonic Evaluation of the Lens Thickness to Axial Length Factor in Primary Closure Angle Glaucoma

Ultrasonic biometry was done in 232 normal eyes and 138 eyes with primary angle closure glaucoma (ACG), using Ultrascan Digital B System IV (10 MHz). The ratio between the lens thickness and the axial length (lens thickness to axial length factor, LAF) was evaluated as a biometric index for assessing the eye with primary ACG in Chinese. LAF of 2.00 was found to be ideal point of demarcation between ACG and normal eyes (i.e., lens thickness equals to 1/5 of axial length). It appears that LAF is helpful i...

Distribution of Axial Length, Anterior Chamber Depth and Lens Thickness of Pre-Operative Cataract Patients in Indonesian Population

Purpose: Biometry measurement of pre-operative cataract patients plays a major role in calculating intraocular lens power. This study aimed to review and determine the distribution of biometry components, such as axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) of pre-operative cataract patient in Indonesian population. Methods: A cross-sectional study data were obtained from 2015-2018 cataract surgery at Prima Husada Citra Hospital, Surabaya, East Java, Indonesia. A total of 1295 eyes with cataract was included in the study based on their medical record. We analyzed the data using descriptive analysis and correlated each variable using the Spearman’s Rho analysis. Results: Mean AL, LT and ACD was 23.81 ± 1.46 mm, 4.49 ± 0.55 mm, 3.25 ± 0.70 mm respectively. Male has longer AL and deeper ACD with (p < 0.001), while LT was found thicker in female (p = 0.005). The increase of AL was accompanied by ACD (r = 0.457;p < 0.001) and a thinner LT (r = -0.101;p < 0.001). Conclusions: LT is increased with age while AL and ACD are shortened with age. There was a positive correlation between AL and ACD, but an inverse correlation between AL and LT.

Lens thickness and associated ocular biometric factors among cataract patients in Shanghai

Background:To evaluate the distribution of lens thickness(LT)and its associations with other ocular biometric factors among cataract patients in Shanghai.Methods:Twenty-four thousand thirteen eyes from 24,013 cataract patients were retrospectively included.Ocular biometric factors including LT,central corneal thickness(CCT),anterior chamber depth(ACD),white-to-white(WTW)distance,anterior corneal curvature,and axial length(AL)were obtained using the IOLMaster700.The associations between LT and general or ocular factors were assessed.Results:The mean age was 62.5±13.6 years and 56.1%were female.The mean LT was 4.51±0.46 mm.The LT was greater in older patients(P<0.001).LT was positively correlated with CCT,while negatively correlated with ACD,WTW,and anterior corneal curvature(P<0.001).Multivariate analysis revealed that increased LT was associated with older age,male gender,thicker CCT,shallower ACD,larger WTW,and flatter anterior corneal curvature(P<0.001).LT changed with a variable behavior according to AL.In short eyes LT increased as AL increased,then decreased with longer AL in normal eyes and moderate myopic eyes,but increased again as AL increased in highly myopic eyes.Thickest LT was found in the 20.01-22mm AL group.The correlation between LT and other biometric factors remained significant when stratified by ALs.Conclusions:In a large Chinese cataractous population,we found that the thicker lens may be associated with older age,male gender,thicker CCT,shallower ACD,larger WTW,and flatter anterior corneal curvature.As AL increased,the change of LT was nonlinear,with the thickest lens seen in the 20-22mm AL group.

Increased aquaporin-1 levels in lens epithelial cells with primary angle-closure glaucoma

AIM： To determine the levels of aquaporin-1（AQP-1） in the lens epithelial cells（LECs） of primary glaucoma and to clarify its correlation with lens thickness.METHODS： This study comprised 64 eyes of 64 patients with primary glaucoma, who were divided into 3 groups： 25 eyes of 25 patients with acute primary angle-closure glaucoma（APACG）, 19 eyes of 19 patients with chronic primary angle-closure glaucoma（CPACG） and 20 eyes of 20 patients with primary open angle glaucoma（POAG）. This study also included 12 eyes of 12 patients with senile cataract as controls. The levels of AQP-1 in LECs were examined by real-time quantitative polymerase chain reaction（RT-q PCR） and immunohistochemistry. The lens thickness was measured by A-scan ultrasonography. RESULTS： The AQP-1 m RNA levels of LECs were 0.84±0.27, 0.69±0.34, 0.44±0.19 and 0.51±0.21 in APACG, CPACG, POAG and senile cataract group, respectively. The levels of AQP-1m RNA were significantly higher in PACG groups compared with those in senile cataract and POAG group（all P〈0.05）. The immunohistochemistry showed the AQP-1 expression were strong-positive in PACG groups, but weak-positive in senile cataract and POAG group. A positive correlation was found between AQP-1 m RNA levels and the lens thickness（r=0.645, P〈0.001）. CONCLUSION： These findings show that the higher expression of AQP-1 in LECs may contribute to increased lens thickness, which might be associated with the occurrence and development of PACG.