Contrast sensitivity (CS) and tear film (TF) changes are noted in late postoperative period after upper blepharoplasty (UB), while the same was rarely investigated in the early postoperative period. The reason for aforementioned improvement of vision quality is unclear. Suggested explanations include changes in higher-order aberrations, elimination of the overlay effect created by excess skin on the upper eyelids and/or eyelashes directed toward the eyelid, or changes in corneal topography (CT) and keratometry.

Furthermore, there is no consensus on the best technique for UB. Due not only to different surgical techniques, but also to different methods of measuring the tear film quality, it is very difficult to quantify the aforementioned studies.

While changes in tear volume parameters and changes in tear film (TF) rupture have been investigated in detail, changes in the lipid layer have rarely been investigated.

According to previous studies, there are different findings about changes in CT after UB.

The aim of the research is to determine whether there are anatomical (CT) and functional (TF and CS) changes in subjects with functional dermatochalasis before the procedure and in a month-long postoperative period.

The research is conducted on examinees diagnosed by clinical examination with functional dermatochalasis with the exclusion of examinees with ocular or systemic conditions affecting TF, best corrected visual acuity or CT.

Detailed medical history and ophthalmologic examination will be performed with grading of the external appearance of the upper eyelids. All diseases and conditions that can lead to changes in CS, TF or corneal defects will be noted. Preoperatively all subjects will have CS recorded in photopic conditions, TF analysis and CT (Keratograph 5M, OCULUS Optikgeraete GmbH, Wetzlar, Germany). UB will be performed in the operating room at the UED. At first (seven days postoperatively) and second (one month postoperative) check-up a CS check will be performed at the UED and TF analysis and CT at Lens LTD.

Dermatochalasis is an age-related condition characterized by the development of folds of excess skin on the upper eyelid with loss of skin elasticity. The mechanical pressure created by the accumulation of excess fat tissue and skin over the upper eyelid leads to a feeling of heaviness and narrowing of the peripheral visual field, which is an indication for surgical treatment. In addition to widening the field of vision, it has been noted that upper blepharoplasty (UB) also has an impact on the subjective improvement of vision postoperatively. Although no difference in best corrected visual acuity was observed pre- and postoperatively, it was noted that contrast sensitivity (CS) improves after UB, especially in the late postoperative period, while the same was rarely investigated in the early postoperative period. The exact reason for the postoperative increase in CS is not clear. Suggested explanations include changes in higher-order aberrations, elimination of the overlay effect created by excess skin on the upper eyelids and/or eyelashes directed toward the eyelid, or changes in corneal topography (CT) and keratometry.

Furthermore, there is no consensus on the best technique for UB. Due not only to different surgical techniques, but also to different methods of measuring the tear film quality, it is very difficult to quantify the aforementioned studies.

While changes in tear volume parameters and changes in tear film (TF) rupture have been investigated in detail, changes in the lipid layer have rarely been investigated.

According to previous studies, there are different findings about changes in CT after UB.

The aim of the research is to determine whether there are anatomical (CT) and functional (TF and CS) changes in subjects with functional dermatochalasis before the procedure and in a month-long postoperative period.

The research is conducted on examinees diagnosed by clinical examination with functional dermatochalasis. Functional dermatochalasis is considered excess skin on the upper eyelid with subjective difficulties due to obstructing the upper part of visual field: swelling of the eyelids in the morning with difficulties in opening the eyes, use of the frontal musculature to be able to have at least a partial width of the field of vision in the upper part that is adequate for daily functioning, and headaches. Exclusion criteria are: history of corneal refractive surgery, pterygium, glaucoma, nuclear sclerosis > 4th degree, severe dry eye, age-related macular degeneration, neuro-ophthalmological diseases, use of hormone therapy, diabetic retinopathy or condition after panretinal photocoagulation. Corneal pathologies such as keratoconus and gross eyelid malposition conditions such as entropion, ectropion and marked laxity of the eyelids are also grounds for exclusion from the study.

The external appearance of the upper eyelids of all subjects will be graded in accordance with previous studies. All subjects will have a detailed personal and ophthalmological history taken, and a biomicroscope examination of the anterior segment and fundus. All diseases and conditions that can lead to changes in CS, TF or corneal defects will be noted. Preoperatively all subjects will have CS recorded in photopic conditions using the Pelli-Robson table, TF analysis and CT (Keratograph 5M, OCULUS Optikgeraete GmbH, Wetzlar, Germany). The CS test will be performed at the University Eye Department, University Hospital Center Osijek (UED), while the TF analysis and CT will be performed at Lens LTD, Zrinjevac 4, 31000 Osijek, completely free of charge. The need for cooperation with Lens LTD arose due to the fact that at UED there is no device for testing the function of the TF, as well as no apparatus for CT. UB will be performed in the operating room at the UED using technique of removing only excess skin without the underlying part of the orbicularis muscle from the upper eyelids. At first (seven days postoperatively) and second (one month postoperative) check-up a CS check will be performed at the UED and TF analysis and CT at Lens LTD. All data will be statistically processed and used in the form of congress announcements and scientific papers in the journal.

Inclusion Criteria:

• Patients with functional dermatochalasis on the upper eyelid with subjective difficulties due to obstructing the upper part of visual field: swelling of the eyelids in the morning with difficulties in opening the eyes, use of the frontal musculature to be able to have at least a partial width of the field of vision in the upper part that is adequate for daily functioning, and headaches.

Exclusion Criteria:

• History of corneal refractive surgery, pterygium, glaucoma, nuclear sclerosis > 4th degree, severe dry eye, age-related macular degeneration, neuro-ophthalmological diseases, use of hormone therapy, diabetic retinopathy or condition after panretinal photocoagulation. Corneal pathologies such as keratoconus and gross eyelid malposition conditions such as entropion, ectropion and marked laxity of the eyelids are also grounds for exclusion from the study.

Examinees complaining of subjective difficulties due to excess skin on the upper eyelid. All examinees will be examined in University Eye Department, University Hospital Osijek