# Crossed Cylinder Calculator > Calculates resultant lens prescription from existing lens and over-refraction data. (iPhone/iPad app by Alta Vista LLC.) - Source: https://appshunter.io/ios/app/crossed-cylinder-calculator/id963247457 (this page in markdown: same URL + `.md`) - Developer: [Alta Vista LLC](https://appshunter.io/developer/954937423) - Category: Medical, Health & Fitness - Price: $1.99 - Rating: 4.00/5 from 1 App Store ratings · 2 written reviews indexed - Age rating: 4+ - Requires: iOS 9.0 · 15 MB - Languages: English - Released: 2015-02-11 - Data updated: 2026-06-10 - Monetization: paid - User reviews in markdown: https://appshunter.io/ios/app/crossed-cylinder-calculator/id963247457/reviews.md ## What is Crossed Cylinder Calculator? Determine resultant lens over existing lens combined with over refraction. Makes contact lens fitting more accurate. Useful in refining high powered eyeglass prescriptions using over refraction. Quick and easy to use application determines resulting contact lens prescription or spectacle prescription using lens currently worn and over refraction data. Exact results or round to one quarter diopter. ## Key features - Accurate contact lens fitting - Refines eyeglass prescriptions - Calculates resultant lens prescription - Uses existing lens and over-refraction data - Provides exact or rounded results ## Recent user reviews (2 of 2) All indexed reviews: https://appshunter.io/ios/app/crossed-cylinder-calculator/id963247457/reviews.md ### 4/5 — Axis error *2015-09-03, version 1.1* Past version This app has a drum system and is easy to use, I have found some glitches. Firstly, the axis drums have an erroneous axis of 169 which should be 160. Secondly, a negative axis appears. This is not a big problem in that by subtracting that number from 180 gives the correct axis. For example, if lens worn is +2.50-1.75x167 and the Over Refraction is Plano-0.25x30, the result is +2.50-1.75x-9. -9 is equivalent to x171. Update: Axis problem is fixed. Recommend increasing range of spheres to + / - 20D. Or having an optional window to type in the needed power. Typing in an axis may save time spinning the drum. ### 1/5 — Axis incorrect *2015-08-03, version 1.0* I would gladly change my rating if this bug is fixed but I can’t find anywhere to contact the developer. It calculates axis wrong. If you enter +2.00-1.75x175 for glasses and over refract 0.00-0.50x90 the result it gives is +1.51-1.26x83 (it won’t round this result either), which is incorrect. I cannot currently recommend purchasing this app until the error is corrected. ## Frequently asked questions about Crossed Cylinder Calculator ### What is the Crossed Cylinder Calculator used for? The Crossed Cylinder Calculator is used to determine the resultant lens prescription when combining an existing lens with over-refraction data. This is particularly helpful for making contact lens fittings more accurate and for refining high-powered eyeglass prescriptions. ### How accurate are the results from the Crossed Cylinder Calculator? The application provides exact results for the resultant contact lens or spectacle prescription. It also offers the option to round these results to one quarter diopter for practical application. ### What is the price of the Crossed Cylinder Calculator? The Crossed Cylinder Calculator is available for a one-time purchase price of $1.99. ### On which devices can I use the Crossed Cylinder Calculator? The Crossed Cylinder Calculator is supported on iPhone, iPad, and iPod devices, making it accessible for a wide range of Apple users in the medical field. ### How often is the Crossed Cylinder Calculator updated? The latest version of the Crossed Cylinder Calculator is 1.12, which was last updated on January 18, 2022. This indicates a stable application with periodic maintenance. ### What is the age rating for the Crossed Cylinder Calculator? The Crossed Cylinder Calculator has an age rating of 4+, meaning it is suitable for users of all ages and contains no mature content. ### Does the Crossed Cylinder Calculator have ads? No, the Crossed Cylinder Calculator does not contain advertisements. As a paid application, users can expect an ad-free experience. ### What do users think of the Crossed Cylinder Calculator? Based on available data, the Crossed Cylinder Calculator has a rating of 4.0 stars from 1 rating. This suggests a positive reception from its users. ## Version history (last 4 releases) ### 1.12 — 2022-01-18 Code update ### 1.11 — 2018-09-21 update to swift code ### 1.1 — 2015-08-26 Fixed axis calculations. ### 1.0 — 2015-02-09 No release notes. ## Apps similar to Crossed Cylinder Calculator | App | Rating | Price | Category | | --- | --- | --- | --- | | [Atlas of Ophthalmology](https://appshunter.io/ios/app/atlas-of-ophthalmology/id448650383) | 1.0 (1) | Free | Medical | | [CalcRx](https://appshunter.io/ios/app/calcrx/id1005970010) | 4.7 (14) | Free | Medical | | [ModMed Practice](https://appshunter.io/ios/app/modmed-practice/id906481220) | 2.8 (338) | Free | Medical | | [9 Gaze](https://appshunter.io/ios/app/9-gaze/id1173442389) | 4.6 (22) | Free | Medical | | [Home Vision Check](https://appshunter.io/ios/app/home-vision-check/id1509064548) | 5.0 (11) | Free | Medical | | [Eye GIFs - Patient Education](https://appshunter.io/ios/app/eye-gifs-patient-education/id1468986693) | 3.8 (14) | Free | Medical | ## More apps by Alta Vista LLC - [Transpose Eyeglass Prescription](https://appshunter.io/ios/app/transpose-eyeglass-prescription/id954937424) - [Vertex Conversion](https://appshunter.io/ios/app/vertex-conversion/id957228139) - [ICD-10 Reference for Optometry](https://appshunter.io/ios/app/icd-10-reference-for-optometry/id1028600368) All apps by Alta Vista LLC: https://appshunter.io/developer/954937423 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-10.*