ObjectiveWith the developing medical technology, functionalendoscopic sinus surgery (FESS) is appliedquite frequently in paranasal sinus surgeries inotolaryngology practice. However, due to the nasalcavity structure, variations and neighborhoods,it is the body cavity that should be considered.Preoperative paranasal sinus computed tomography(CT) evaluation of the nasal cavity is mandatory. Inour study, we especially aimed to reveal olfactoryfossa variations with paranasal CT. With this article,we aimed to define the pre-FESC variations of thepeople in the Lakes District and to increase theawareness of surgeons against complications in thepreoperative period.Material and MethodsThe images of the patients who applied to our hospitalfor sinusitis and underwent paranasal sinus CTbetween 01.01.2019 and 15.03.2019 were analyzedretrospectively by two radiologists. 112 men and 88women; A total of 200 patients aged 18-69 years wereincluded. The measurements of the lateral laminae inthe right and left nasal cavity for each patient andthe depths of the olfactory fossa were classifiedaccording to Keros types. The lateral lamina heightwas determined and the patients were classified into3 groups. Depths of 1-3 mm for keros type 1, 4-7 mmfor keros type 2 and 8-16 mm for keros type 3 weretaken. The obtained data were then compared withsimilar data in the literature.ResultsLateral lamina lengths for right side; 144 (72%)individuals in the keros type 1 group and 56 (28%)individuals in the keros type 2 group were classified,and 142 (71%) individuals in the keros type 1 groupand 58 (29%) individuals in the keros type 2 groupwere classified for the left side. In the keros type1 variation on the right, 76 individuals were maleand 68 individuals were female. In the keros type2 variation on the right, 36 individuals were maleand 20 individuals were female. In the keros type 1variation on the left, 74 individuals were male and 68individuals were female. In the keros type 2 variationon the left, 38 individuals were male and 20 individualswere female. No individuals were classified for rightand left in the keros type 3 group. Right; The meanlamina lateralis length was calculated as 2,49±0,76in the keros type 1 variation, and 4,21±0,54 in thekeros type 2 variation. On the left; The mean lengthof the lamina lateralis in the keros type 1 variationwas calculated as 2,33±0,79, while the mean lengthin the keros type 2 variation was calculated as4,2±0,54. The number of individuals with differentkeros types in the right and left measurements andkeros asymmetry was observed as 52 (26%) out of200 individuals.ConclusionWhile keros type 1 was observed most frequently inour study with a rate of 71.5%, Keros Type 3 wasnever encountered, and we found keros asymmetryas 26% in our study. In our study, type 1 variant wasobserved at a high rate for both genders, but it didnot create a statistically significant difference. In asimilar study conducted in the literature, significantdifferences were observed in the percentages, and weinterpreted this difference as the variation belongingto the people of the Lakes District. In particular, nasalcavity variations show various variations in differentregions. The absence of type 3 variation in the LakesDistrict is an advantage for this region. Althoughthe type 1 variation with the smallest depth of theolfactory fossa does not make a statistically significantdifference, the highest number of observations is alsoan advantage for the people of the Lakes District, asit carries less risk of complications.