The role of dry eye disease in cataract and refractive surgery

El síndrome de ojo seco (DED) puede jugar un papel importante en las cirugías oftálmicas con fines refractivos tanto corneales (tratamiento corneal laser) como cristalinianas (cirugía de catarata) pero también en aquellas cuyo fin es controlar la presión intraocular en pacientes que sufren de glaucoma. El objetivo principal de esta tesis se refiere a la aplicación de una serie de pruebas diagnósticas, de mínimamente a no-invasivas, sugeridas por el Tear Film & Ocular Society Dry Eye WorkShop II (TFOS DEWS II) que pueden ayudar a mejorar los resultandos refractivos y visuales en la cirugía oftálmica actual. La cirugía de cristalino, particularmente la cirugía moderna de catarata y la refractive lens exchange (RLE), centra la primera sección de la tesis. En realidad, el DED no está presente solo como complicación post-operatoria, sino que también es responsable de resultados refractivos y visuales no deseados dado que parte del examen pre-operatorio en la cirugía del cristalino puede verse influida por una película lagrimal deficiente (por ej. biometría ocular y topografía corneal). La literatura revisada ha demostrado poca información en el uso de técnicas avanzadas para evaluar la película lacrimal en pacientes que se someten a cirugía de cristalino, siendo estos hallazgos los más importantes para evitar resultados subóptimos después de la intervención. Posteriormente, en la cirugía refractiva corneal moderna, a pesar de la seguridad y efectividad en la corrección de errores refractivos tales como miopía, hipermetropía y astigmatismo, el DED post-quirúrgico sigue siendo un problema recurrente y unas de las complicaciones más referidas por los pacientes. Recientemente, nuevas técnicas (por ej. small incision lenticule extraction (SMILE)) han sido introducidas con el fin de reducir el desarrollo de DED. El uso de la microscopia confocal in-vivo, así como un programa automático de análisis, has sido incluidos para proporcionar resultados objetivos más rápido que puedan ser comparados con la cirugía de la córnea tradicional (e.g. laser-assisted in situ keratomileusis (LASIK)).El manejo de glaucoma mediante colirios oculares con preservantes puede llevar a deterioro de la superficie ocular con una larga proporción de pacientes con quejas del DED tanto como signos (como enrojecimiento ocular) tanto como síntomas (como incomodidad ocular, fotofobia, etc.). De los nuevos procedimientos oculares para controlar la presión intraocular reduciendo la necesidad del manejo tópico, la cirugía de glaucoma minimamente invasiva (MIGS) es prometedora también en mejorar la homeostasis de la superficie ocular. Sin embargo, muy poco ha sido investigado y la necesidad de una mejor comprensión ha llevado a administrar una serie de pruebas avanzadas para el diagnóstico de ojo DED con objeto de revelar los resultados a corto plazo sometidos a MIGS. Los estudios de investigación detallados en esta tesis evalúan una serie de técnicas avanzada de diagnóstico para comprender el papel de la DED en los procedimiento actuales de cirugía oftálmica con propósitos refractivos y visuales pero también para el manejo de enfermedades como el glaucoma. Asimismo, dichos estudios tratan de descubrir cual son las pruebas más importantes, mínimamente o no-invasivas, capaces de revelar el papel del DED en la cirugía oftálmica que llevarían a una mejora en los resultados tanto refractivos como visuales, así como los referidos por los pacientes.Dry eye disease (DED) can play an important role in ophthalmic procedures with refractive aims such as those involving the cornea (corneal laser surgery) or the crystalline lens (refractive lensectomy or cataract surgery) but also in the treatment of other conditions such as glaucoma. This thesis describes the application of a series of minimally to non-invasive diagnostic DED tests recommended by the recent Tear Film & Ocular Society Dry Eye WorkShop II (TFOS DEWS II) to help to improve the understanding of the impact of dry eye on the refractive and visual outcomes in the ophthalmic surgery and the impact of ophthalmic surgery on the ocular surface. Intraocular lens surgery, in particular modern cataract and refractive lens-exchange (RLE) surgery, is the focus of the first section of the thesis. In fact, DED is not only present as a post-operative complication but can also be responsible for sub-optimal refractive and visual outcomes since parts of the pre-operative examination pathway can be influenced by a depleted tear film (e.g. biometry and corneal topography). A literature review suggests little evidence of the routine use of advanced tear film assessments in patients undergoing intraocular lens surgery and there is little information on which DED findings are most important to avoid suboptimal clinical outcomes. Studies were carried out to explore the most relevant DED tests as recommended by the TFOS DEWS II. The key findings were validated questionnaires such as Ocular Surface Disease Index (OSDI) and Dry Eye Questionnaire 5-items (DEQ-5) and tear metrics such as non-invasive keratograph break-up time (NIKBUT), tear film volume (TMH) and tear osmolarity. In modern corneal refractive surgery, despite numerous publications and studies demonstrating the safety and efficacy in correcting refractive errors such as myopia, hyperopia and astigmatism, post-operative DED is still problematic and of the most common complications after surgery. Recently, newer techniques (e.g. small incision lenticule extraction (SMILE)) have been introduced with the aim of providing excellent visual outcomes whilst overcoming some of the limitations of more established procedures including undesirable alterations to corneal nerve structure and function and DED development. The use of in-vivo confocal microscopy was used to compare corneal nerve structure after SMILE with that seen after traditional laser-assisted in situ keratomileusis (LASIK). The results showed FS-LASIK surgery had more impact on DED symptomatology, TMH and NIKBUT and has led to significant change to the corneal nerve fibre metrics considered than SMILE surgery. Glaucoma management with topical preserved eyedrops can lead to deterioration of the ocular surface in a large proportion of patients with DED issues in terms of signs (e.g. ocular redness) and symptoms (grittiness, photophobia, etc.). Of the newer surgical procedures designed to control intraocular pressure reducing the need for topical management, minimally-invasive glaucoma surgery (MIGS) seems to be promising and could improve the homeostasis of the ocular surface in glaucoma patients. However, very little research on this topic has been published and an advanced pilot investigation to explore the use of a diagnostic battery of tests for DED after MIGS was carried out. Reduction in IOP was achieved by the procedure together with the reduction in DED symptomatology, increase of stability of the tear film and improvement of the ocular surface staining. In summary, the research studies detailed in this thesis use a series of advanced diagnostic techniques primarily to understand the role of DED in patients undergoing ophthalmic procedures for refractive and visual indications but also in patients being treated for glaucoma. They also explore which are the most important tests, in terms of identifying the impact of DED in ophthalmic surgery. Better diagnosis and management of DED in patients undergoing ophthalmic surgery will lead to optimal refractive, visual and patient-reported outcomes

The role of dry eye disease in cataract and refractive surgery

Dry eye disease (DED) can play an important role in ophthalmic procedures with refractive aims such as those involving the cornea (corneal laser surgery) or the crystalline lens (refractive lensectomy or cataract surgery). This thesis describes the application of a series of minimally to non-invasive diagnostic DED tests recommended by the recent Tear Film & Ocular Society Dry Eye WorkShop II (TFOS DEWS II) to help to improve the understanding of the impact of dryeye on the refractive and visual outcomes in the ophthalmic surgery and the impact of ophthalmic surgery on the ocular surface.Intraocular lens surgery, in particular modern cataract and refractive lens-exchange (RLE) surgery, is the focus of the first section of the thesis. In fact, DED is not only present as a post-operative complication but can also be responsible for sub-optimal refractive and visual outcomes since parts of the pre-operative examination pathway can be influenced by a depleted tear film (e.g. biometry and corneal topography). A literature review suggests little evidence ofthe routine use of advanced tear film assessments in patients undergoing intraocular lens surgery and there is little information on which DED findings are most important to avoid suboptimal clinical outcomes. Studies were carried out to explore the most relevant DED tests as recommended by the TFOS DEWS II. The key findings were that pre-operative DED metrics such as reduced tear meniscus height (<0.20 mm) together with increased DED symptoms measured with Ocular Surface Disease Index (OSDI) (score ≥13) were potentially relevant to increase the chance of having less accurate refraction and poorer visual outcomes after lens surgery. Contrarily, Dry Eye Questionnaire 5-items (DEQ-5), that is a useful tool to evaluate ocular comfort, might be not designed to consider visual function that could potentially be affected by DED or cataract and might be not a good sensitive indicator of the refractive and visual outcomes after lens surgery.In modern corneal refractive surgery, despite numerous publications and studies demonstrating the safety and efficacy in correcting refractive errors such as myopia, hyperopia and astigmatism, post-operative DED is still problematic and of the most common complications after surgery. Recently, newer techniques (e.g. small incision lenticule extraction (SMILE)) have been introduced with the aim of providing excellent visual outcomes whilst overcoming some of the limitations of more established procedures including undesirable alterations to corneal nerve structure and function and DED development. The use of in-vivo confocal microscopy was used to compare corneal nerve structure after SMILE with that seen after traditional laser-assisted in situ keratomileusis (LASIK). The results showed FS-LASIK surgery had more impact on the corneal nerve fibre metrics (up to 75% of reduction) compared to SMILE surgery (up to 23%). Additionally, DED symptoms after FS-LASIK observed a significant two to four-fold increase (OSDI and DEQ-5) where also tear volume significantly decreased after surgery (from 0.32 ± 0.13 to 0.22 ± 0.09 mm).In summary, the research studies detailed in this thesis use a series of advanced diagnostic techniques primarily to understand the role of DED in patients undergoing ophthalmic procedures for refractive and visual indications. They also explore which are the most important tests, in terms of identifying the impact of DED in ophthalmic surgery. Better diagnosis and management of DED in patients undergoing ophthalmic surgery will lead to optimal refractive, visual and patient-reported outcomes