Evaluation of the Effect of Cataract Surgery on Cognitive Function in Very Elderly Patients

Study design: prospective, monocentric, epidemiological study: non-interventional. The drafting of the protocol follows the order proposed by the STROBE check-list for the publication of the observational studies where applicable.

There is no agreement between promoter and clinical center.

There is no agreement between promoter and financier: the study has no funding. The study is also carried out for the purpose of completing a thesis.

Rational

The constant aging of the population in western countries has led to an increase in the incidence of visual deficits in the elderly, the incidence of cataract is around 68%, at the same time this category of subjects frequently has cognitive deficits that can be minimal or severe as in the case of dementias.

The individual's visual capacity is correlated with the neurological progression of these morbid states. Numerous studies have long sought a correlation between sensory (visual and auditory) functionality and cognitive faculties in old age, defining how sensory functions can be considered indicators of the integrity of the central nervous system.

Further studies, always focused on this current research, focused on a correlation between the improvement of visual acuity through the IOL (Intra Ocular Lens) implant and the improvement of cognitive faculties. Further studies have focused their attention not only on cognitive faculties, but on the psychological aspect in terms of improving the quality of life following cataract surgery. Simultaneously, Cataract surgery has been referred as one the most effective healthcare intervention to prevent and lower the risk of falls, hips and lower limbs fracture, trauma and social isolation.

The improvement of the visual capacity, the cognitive faculties and the psychological state of the elderly patient are certainly useful elements for improving the quality of life of the subject but also for the caregiving burden on the elderly patient by the caregivers and the NHS. A 1998 study found a strong association between visual impairment (caused by altered contrast sensitivity, reduced field of vision and the presence of cataracts) and the increase in falls in the elderly.

Materials and methods

Patients will be enrolled during the filter visits of the ophthalmology clinic: whenever the need for replacement of the operative lens will be diagnosed, the patient will be offered to participate in the data collection by providing the information sheet. Subsequently consent will be collected. Data collection will be undertaken when the consent is signed. An identification code will be assigned exclusively to each patient. The patient's personal data will be entered through the creation of the Patient's list, to keep personal data confidential.

In no case will experimental treatments be provided to the patient: the study includes a collection of clinical information already normally collected during preoperative visits, outpatient visits and during follow-up checks.

The research will be set as a longitudinal observational study where will be compared in each patient the parameters analyzed in the 6 months prior to the cataract operation and in the 3 months following the operation itself.

The cognitive state will be measured over time: during enrollment, on the day of surgery, 20 days after surgery and 3 months after surgery.

Patients will be enrolled during the first cataract filter visit, will be submitted to simple questions and their clinical data will be collected.

A comparison will also be made in terms of incidence of neuro-cognitive and delirium problems in relation to the patient's age and cataract surgery. The great elderly population has a higher risk to encounter a momentaneous cognitive disfunction, due to psycological and physical stress induced by surgery and anesthesia. This study, considering this important element, will indirectly estimate the safety of cataract surgery. The post-operative delirium incidence in a surgical ward is considered an important parameter of quality of care in terms of patient's care and technical management in the ward.

The information sheet will be provided during the filter visit for the insertion of the patient on the waiting list for cataract surgery and consent will be collected after this.

The following parameters will be analyzed: demographic variables, level of education, presence of relatives during the visit, patient history of proximal and remote patient, home therapies, performed analyzes of practice during outpatient visits: BCVA visual acuity (ETDRS optotype tables), microscopy endothelial, OCT macula and optic nerve to exclude the presence of a maculopathy and a deficit of nerve fibers such as to affect the improvement of visual and cognitive function.

Following the collection of the consent, questionnaires will be provided to the patients enrolled to measure the functional cognitive capacity of the subject such as:

Quality of life, Catquest 9SF. The Catquest evaluation consists of 9 questions, evaluating the perceived quality of vision in routine activities like reading, shopping, recognizing individuals or doing recreational activities. The 9 questions present a speicific scale of 5 measures, from "Great Difficult" to "No difficult". The rationale beneath this test is to evaluate the ratio between the personal perception of visual function before and after surgery, evaluating in parallel trends of the mean of the scores calculated. A comparison will be also set between eleders and great elders, to evaluate eventual differences between the perceived result of surgery and the real visual acuity.

Scale of evaluation of daily life activity, Barthel Index. Many clinical studies associated the surgical removal of opacified lens with an increase of independence, due to the increase of visual function. To measure eventual changes, the Barthel Index has been chosen and added inside the protocol. The Barthel scale is an ordinal scale used to measure performance in activities of daily living (ADL). Each performance item is rated on this scale with a given number of points assigned to each level or ranking. This test is used by general physicians, physiotherapists, neurologists and rehabilitation nurses to calculate the trend of physical independence of an individual. This Index evaluates the physical necessities in daily activities like personal hygiene, Mobility, feeding, dressing, bladder control and bowels. The evaluation in this case consists on a score between 0-100 where 100 means complete independence and 0 absolute dependence on someone else.

Cognitive state measured with the Six Item Cognitive Impairment Test (6CIT). Number of questions: 6. Time taken to perform: 3-4 minutes. Score: the 6CIT uses an inverse score and questions are weighted to produce a total out of 28. Scores of 0-7 are considered normal and 8 or more significant. Advantages: the test has high sensitivity without compromising specificity, even in mild dementia. It is easy to translate linguistically and culturally. Disadvantages: the main disadvantage is in the scoring and weighting of the test, which is initially confusing; however, computer models have simplified this greatly.

Probability statistics: at the 7/8 cut-off: Overall figures - sensitivity = 90%, specificity = 100%; in mild dementia, sensitivity = 78%, specificity = 100%. Differently from older studies, the choice of this evaluation method The quickness of the administration of the test and more importantly, the exclusive use of question, and not the use of visual function provides to the study a more complete and purified view of the cognitive function, configuring this study as a innovation in the field.

Following the secondary outcomes, the corneal behavior will be measured between the different groups, focusing on the age criteria. Considering a physiological lowering of the quality of the cornea, the phacoemulsification is a physical stress for the ocular structure, raising the risk of corneal decompensation. To tangibly measure the corneal behavior, corneal thickness and corneal endothelial cells density have been chosen as main parameters. The CSO Perseus 400 (Florence - IT) will be used to study corneal behavior.

At the same time, the Optical Coherence Tomography will be used to evaluate the Macula and the optical nerve modifications after cataract surgery. This evaluation will be set in the highest risk period (up to 30 days after cataract surgery). The Irvine Gass macular edema and optical nerve insults can be a cause of lower visual improvement after a correct cataract surgery. The OPKO OCT/SLO will be used to conduct these measures.

Study Phases and Times

Time 0: patient enrollment (on average 4 months before surgery) Time 1: perioperative time Time 2: check at 20 days Time 3: check at 3 months

It is important to underline that the cognitive tests proposed to patients consist of simple questions that do not depend on the visual ability of the subject.

Finally, the study will compare the incidence data of neuro-cognitive problems in those who have undergone surgery in relation to the patient's age group and cataract surgery.

Data are analyzed using the R-Software, and using the ANOVA calculation method. Analysis of variance (ANOVA) is a collection of statistical models and their associated estimation procedures (such as the "variation" among and between groups) used to analyze the differences among group means in a sample. With this analysis, the trend of each variable will be analyzed.