Conjunctival changes induced by prostaglandin analogues and timolol maleate: a histomorphometric study

PURPOSE: To compare histological changes induced by antiglaucoma medications in the rabbit conjunctiva. METHODS: Fifty New Zealand rabbits were divided in 5 groups of 10 animals. The left eyes were treated daily with one drop of bimatoprost 0.03 percent, travoprost 0.004 percent, latanoprost 0.005 percent, timolol maleate 0.5 percent or artificial tears containing benzalkonium chloride (BAK) for 30 days. The right eyes served as controls. Superior limbic conjunctival biopsies were performed at the 8th and 30th day in 5 rabbits of each group. The conjunctiva was fixed with 10 percent formaldehyde, followed by HE and PAS staining. Morphohistometric quantitative analyses were performed to evaluate the following parameters: inflammatory infiltrate, epithelial thickness, number of goblet cells, diameter and number of blood vessels. RESULTS: At the 8th and 30th posttreatment days, all groups, except one that received artificial tears, exhibited a diffuse inflammatory infiltrate, composed by lymphocytes and neutrophils, which was denser in the timolol group than in the prostaglandin (PG) analogues groups. At the 30th day, the timolol group also showed an increased subepithelial collagen density and a significant increase in epithelial thickness (p=0.0035). The goblet cell density was significantly increased at the 8th day in the group treated with travoprost (p=0.0006), and at the 30th day in those treated with bimatoprost (p=0.0021) and latanoprost (p=0.009). CONCLUSIONS: Although a moderate, diffuse inflammatory infiltrate was observed in PG-treated eyes, no changes in conjunctival epithelial thickness or subconjunctival collagen density were observed with these medications, suggesting that these drugs induce fewer changes than timolol maleate in the rabbit conjunctiva.

OBJETIVOS: Comparar alterações histológicas induzidas por medicação anti-glaucomatosa na conjuntiva de coelhos. MÉTODOS: Cinqüenta coelhos da raça Nova Zelândia foram divididos em 5 grupos de 10 animais. Os olhos esquerdos foram tratados com uma gota diária de bimatoprosta 0,03 por cento, travoprosta 0,004 por cento, latanoprosta 0,005 por cento, maleato de timolol 0,5 por cento ou lágrimas artificiais contendo cloreto de benzalcônio (BAK) por 30 dias. Os olhos direitos serviram como controles. Foram realizadas biópsias conjuntivais límbicas superiores no 8º e 30º dias em 5 coelhos de cada grupo. A conjuntiva foi fixada com formaldeído 10 por cento, seguido por coloração de HE e PAS. Foi realizada análise quantitativa morfohistométrica para avaliar os seguintes parâmetros: infiltrado inflamatório, espessura epitelial, número de células caliciformes, diâmetro e número de vasos sanguíneos. RESULTADOS: No 8º e 30º dias de tratamento, todos os grupos, exceto aquele que recebeu lágrimas artificiais, exibiram infiltrado inflamatório difuso, composto por linfócitos e neutrófilos, sendo mais denso no grupo timolol do que nos grupos dos análogos de prostaglandinas. No 30º dia, o grupo timolol apresentou um aumento na densidade de colágeno subepitelial e um aumento significativo da espessura epitelial (p=0,0035). A densidade de células caliciformes aumentou significativamente no 8º dia no grupo tratado com travoprosta (p=0,0006), e no 30º dia nos grupos tratados com bimatoprosta (p=0,0021) e latanoprosta (p=0,009). CONCLUSÕES: Embora tenha sido observado um infiltrado inflamatório difuso e moderado nos olhos tratados com análogos de prostaglandinas, não houve alterações na espessura epitelial conjuntival ou densidade colágena subepitelial com essas medicações, sugerindo que essas drogas induzem menores alterações que o maleato de timolol na conjuntiva de coelhos.

Conjunctival changes induced by prostaglandin analogues and timolol maleate: a histomorphometric study.

PURPOSE: To compare histological changes induced by antiglaucoma medications in the rabbit conjunctiva. METHODS: Fifty New Zealand rabbits were divided in 5 groups of 10 animals. The left eyes were treated daily with one drop of bimatoprost 0.03%, travoprost 0.004%, latanoprost 0.005%, timolol maleate 0.5% or artificial tears containing benzalkonium chloride (BAK) for 30 days. The right eyes served as controls. Superior limbic conjunctival biopsies were performed at the 8th and 30th day in 5 rabbits of each group. The conjunctiva was fixed with 10% formaldehyde, followed by HE and PAS staining. Morphohistometric quantitative analyses were performed to evaluate the following parameters: inflammatory infiltrate, epithelial thickness, number of goblet cells, diameter and number of blood vessels. RESULTS: At the 8th and 30th posttreatment days, all groups, except one that received artificial tears, exhibited a diffuse inflammatory infiltrate, composed by lymphocytes and neutrophils, which was denser in the timolol group than in the prostaglandin (PG) analogues groups. At the 30th day, the timolol group also showed an increased subepithelial collagen density and a significant increase in epithelial thickness (p=0.0035). The goblet cell density was significantly increased at the 8th day in the group treated with travoprost (p=0.0006), and at the 30th day in those treated with bimatoprost (p=0.0021) and latanoprost (p=0.009). CONCLUSIONS: Although a moderate, diffuse inflammatory infiltrate was observed in PG-treated eyes, no changes in conjunctival epithelial thickness or subconjunctival collagen density were observed with these medications, suggesting that these drugs induce fewer changes than timolol maleate in the rabbit conjunctiva.