Relationships between corneal biomechanics and the structural and functional parameters of glaucoma damage / Relações entre a biomecânica da córnea e os parâmetros estruturais e funcionais do dano do glaucoma

ABSTRACT Purpose: To investigate the relationships between (i) thickness of the retinal nerve fiber layer, optic nerve head topography, and visual field parameters and (ii) corneal biomechanical properties in normal controls and patients with ocular hypertension and primary open-angle glaucoma. Methods: This observational, cross-sectional study included 68 eyes with primary open-angle glaucoma, 99 eyes with ocular hypertension and 133 control eyes. Corneal biomechanical properties, optic nerve head topographic features, retinal nerve fiber layer thickness, and visual fields were assessed in all cases. Corneal biomechanical properties, retinal nerve fiber layer thicknesses, and optic nerve head topographic features were compared among the groups. The associations between structural and functional measures of glaucomatous damage and corneal biomechanical factors were also evaluated. Results: Significantly lower corneal hysteresis and corneal resistance factor values were observed in the primary open-angle glaucoma and ocular hypertension groups as compared with the control group, but there were no significant differences between the primary open-angle glaucoma and ocular hypertension groups. In the ocular hypertension group, no associations were observed between the corneal hysteresis and corneal resistance factor with values and the structural and functional parameters. In the primary open-angle glaucoma group, positive correlations were observed between the corneal hysteresis values and the global retinal nerve fiber layer thickness (p<0.01, r=0.27), mean retinal nerve fiber layer thickness (p<0.01, r=0.33), and mean deviation (p<0.01, r=0.26), and negative correlations were observed between the corneal resistance factor values, and the cup area (p<0.01, r=-0.39), cup-to-disk ratio (p=0.02, r=-0.28), linear cup-to-disk ratio (p=0.02, r=-0.28), and cup shape (p=0.03, r=-0.26). In the control group, weak correlations were detected between the corneal hysteresis and the cup area (p=0.03, r=0.19), cup-to-disk ratio (p=0.01, r=0.21), and linear cup-to-disk ratio (p=0.01, r=0.22). Conclusions: Distinct correlations were identified between the corneal hysteresis and corneal resistance factor values and the functional and structural parameters in the primary open-angle glaucoma and control groups. Corneal hysteresis and corneal resistance factor may have different roles in the pathophysiology of glaucoma.

RESUMO Objetivo: Investigar as relações entre (i) espessura da camada de fibras nervosas da retina, topografia do nervo óptico e parâmetros do campo visual e (ii) propriedades biomecânicas da córnea, em controles normais e pacientes com hiperten são ocular e glaucoma primário de ângulo aberto. Métodos: Este estudo observacional, transversal, incluiu 68 olhos com glaucoma primário de ângulo aberto, 99 olhos com hipertensão ocular e 133 olhos controle. As propriedades biomecânicas da córnea, as características topográficas da cabeça do nervo óptico, a espessura da camada de fibras nervosas da retina e os campos visuais foram avaliados em todos os casos. As propriedades biomecânicas da córnea, a espessura da camada de fibras nervosas da retina e as características topográficas da cabeça do nervo óptico foram comparadas entre os grupos. As associações entre medidas estruturais e funcionais de danos glaucomatosos e fatores biomecânicos da córnea também foram avaliadas. Resultados: Valores de histerese corneana e da resistência corneana foram significativamente menores nos grupos com glaucoma primário de ângulo aberto e hipertensão ocular em com paração ao grupo controle, mas não houve diferenças significativas entre os grupos de glaucoma primário de ângulo aberto e hipertensão ocular. No grupo com hipertensão ocular, não foram observadas associações entre histerese da córnea e o fator de resistência corneana com os valores e os parâmetros estruturais e funcionais. No grupo com glaucoma primário de ângulo aberto foram observadas correlações positivas entre os valores de histerese corneana e a espessura a camada de fibras nervosas da retina (p<0,01, r=0,27), espessura média da camada de fibras nervosas da retina (p<0,01, r=0,33) e desvio médio (p<0,01, r=0,26), e correlações negativas entre o os valores do fator de resistência da córnea e a área de escavação (p<0,01, r=-0,39), a relação escavação/disco (p=0,02, r=-0,28), a relação copo-para-disco linear (p=0,02, r=-0,28) e a forma da escavação (p=0,03, r=-0,26). No grupo controle, correlações foram detectadas entre a histerese da córnea e área de escavação (p=0,03, r=0,19), relação escavação/disco (p=0,01, r=0,21) e relação copo-para-disco linear (p=0,01, r=0,22). Conclusões: Correlações distintas foram identificadas entre histerese da córnea e os valores de resistência da córnea e os parâmetros funcionais e estruturais nos grupos de glaucoma primário de ângulo aberto e controle. A histerese da córnea e o fator de resistência da córnea podem ter diferentes papéis na fisiopatologia do glaucoma.

Comparison of conjunctival impression cytology in primary open angle glaucoma, ocular hypertension and normal subjects / 国际眼科杂志(Guoji Yanke Zazhi)

?AlM:To compare the tear functions and the impression cytology scores of the patients with primary open angle glaucoma ( POAG ) , ocular hypertension ( OHT ) and normal subjects with healthy ocular surface both functionally and clinically. ?METHODS: Eleven eyes of 11 patients with POAG (mean age: 62. 7±6. 1y), 12 eyes of 12 patients ( mean age:62. 8±6. 4y ) with OHT and 12 eyes of 12 normal subjects ( mean age: 62. 9±6. 03y) were included to this prospective study. The patients with POAG and OHT had been recently diagnosed with these diseases and none of them had taken anti - glaucoma treatment before. ln addition to conjunctival impression cytology, tear break-up time ( TBUT ) and basal Schirmer’s tests ( BST ) were performed. lmpression cytology specimens of each group were graded and scored in the range of 0-3 according to Nelson’s method. Kruskal- Wallis analysis and Dunn’s multiple comparison tests were used for statistical analysis. ?RESULTS:The mean BST values were 10. 4±1. 3, 10. 9±1. 2 and 11. 1±1. 1 mm/5min of POAG, OHT and control groups respectively. The differences among the BST values of the POAG, OHT and control group were not statistically significant (P=0. 33). The mean TBUT values were 11. 2±1. 1, 11. 3±1. 1 and 11. 8±1. 2s in POAG, OHT and normal subjects respectively. The differences among the BUT values of the POAG, OHT and control group were not statistically significant (P=0. 35). Six eyes (54. 5%) revealed grade 0 and 5 eyes ( 45. 5%) revealed grade 1 impression cytology scores in POAG group. Six eyes (50%) revealed grade 0 and 6 eyes (50%) revealed grade 1 impression cytology scores in OHT group and 6 eyes (50%) revealed grade 0 and 6 eyes (50%) revealed grade 1 impression cytology scores in normal subjects ( P =0. 97). ?CONCLUSlON: Oxidative stress may cause glaucoma, ocular surface diseases, lacrimal gland malfunction and a decrease in mucus secretion ofgoblet cells in all of the body. There were no significant differences between the impression cytology scores of patients with POAG, OHT and normal subjects.

Comparing acromegalic patients to healthy controls with respect to intraocular pressure, central corneal thickness, and optic disc topography findings.

Aims: The aim was to compare the intraocular pressure (IOP), central corneal thickness (CCT), and optic disc topography fi ndings of biochemically controlled acromegalic patients and the control group and to evaluate the eff ect of the duration of acromegaly and serum growth hormone and insulin-like growth factor-1 (IGF-1) levels on these ocular parameters. Materials and Methods: IOP measurement with Goldmann applanation tonometry, CCT measurement with ultrasonic pachymetry, and topographic analysis with Heidelberg retinal tomograph III were performed on 35 biochemically controlled acromegalic patients and 36 age- and gender-matched controls. Results: Mean IOP and CCT were 14.7 ± 2.9 mmHg and 559.5 ± 44.9 m in the acromegaly patients and 13.0 ± 1.6 mmHg and 547.1 ± 26.7 m in controls (P = 0.006 and P = 0.15, respectively). A signifi cant moderate correlation was found between the duration of acromegaly and CCT (r = 0.391) and IOP (r = 0.367). Mean retinal nerve fi ber layer (RNFL) thickness was signifi cantly lower in the acromegalic patients (0.25 ± 0.05 mm) as compared to controls (0.31 ± 0.09 mm) (P = 0.01). A signifi cant moderate correlation was detected between IGF-1 level and disc area (r = 0.362), cup area (r = 0.389) and cup volume (r = 0.491). Conclusion: Biochemically controlled acromegalic patients showed signifi cantly higher CCT and IOP levels and lower RNFL thickness compared to healthy controls and the duration of disease was correlated with CCT and IOP levels.