OptiDex

Professional Optical Reference for Clinicians

Optical calculators · Contact lens database · Ocular pathology · Clinical trials · Drug reference · Board-style quizzes

Clinical Databases

🔬

Ocular Pathology

202 conditions across 8 specialties — searchable by segment, with epidemiology, pathophysiology, signs, and treatment

Anterior Segment Posterior Segment Glaucoma Neuro-Ophthalm. Uveitis

→

💧

Contact Lens Database

95+ lenses — soft, scleral, hybrid, ortho-K, and specialty — with full parameter tables and Rx search

Daily Disposable Monthly Scleral Toric Ortho-K

→

Reference Libraries

📚

Clinical Trials

30 landmark studies

MARINA · OHTS · ONTT · DEWS II · ATOM · LiGHT · CITT · BEAT-ROP

💊

Drug Reference

54 ocular medications

Glaucoma · Mydriatics · Anti-infectives · Anti-inflammatory · Anti-VEGF · Allergy/Dry Eye

📐

Normal Values

10 reference tables

IOP · RNFL · VF indices · BV norms · Accommodation · VA equivalents · CL fitting

Optical Calculators

Board Exam Preparation

NBEO · KMK · OptoPrep

Optometry Quiz

Clinical vignettes across 10 topics with 3 difficulty levels — posterior segment, glaucoma, neuro, pharmacology, color vision, BV, refraction, and more

Posterior SegmentAnterior SegmentGlaucomaNeuro-Ophthalm.Binocular VisionRefractionContact LensesPharmacologyColor Vision

151

questions

difficulty levels

Start →

ABO · NOCE · NCLE

Optics & Dispensing

Ophthalmic optics, spectacle dispensing, and contact lens technology — for opticians and dispensing exam prep

Ophthalmic OpticsDispensingContact Lens Tech

questions

topic areas

Start →

6Calculators

95+Contact Lenses

202Conditions

30Key Trials

54Drug Entries

234Quiz Questions

For educational and professional reference only. Not for patient-facing diagnostic or treatment decisions. See full disclaimer in footer.

Vertex Distance Conversion

Convert spectacle Rx to contact lens plane (or any target vertex distance). Updates live as you type.

Input Rx & Vertex

Sphere (D)

Cylinder (D)

Spectacle Vertex Distance (mm)

Target Vertex Distance (mm) — use 0 for contact lens

Result

New Sphere

—

New Cylinder

—

Spherical Equivalent

—

at the target plane

Enter values above — results update live.

F' = F / (1 − d·F) | d = vertex shift in meters
Applied independently to sphere & sphere+cyl meridians

Prentice's Rule Calculator

Calculate induced prismatic effect at any point on a lens. Updates live as you type.

Parameters

Lens Power (D)

Decentration (mm)

Direction of Decentration

Eye

Result

Prismatic Effect

—

Base direction: —

Enter values above — results update live.

Δ = P × c | P = power (D), c = decentration (cm)
Base direction follows standard ophthalmic convention

Lens Thickness Calculator

Frame-based edge thickness at nasal, temporal, superior, and inferior edges — accounts for cylinder axis and OC placement.

Prescription

Sphere (D)

Cylinder (D)

Axis (°)

Refractive Index

Center Thickness CT (mm)

Base Curve

Base Curve (D)

AUTO

Edit to override. Change sphere to restore auto.

Frame — Boxing System

Eye Size A (mm)

Bridge (mm)

B-dimension (mm)

PD & OC Placement

Mono PD (mm)

OC Height from bottom (mm)

Eye

Edge Thickness at Frame

—

Sup

—

Inf

—

Nas

—

Tem

Nasal

—

Temporal

—

Superior

—

Inferior

—

H-Decentration

—

OC Vertical Offset

—

Values update live as you type.

r=(n−1)/F×1000mm | sag=y²/(2r) | ET=CT+sag_back−sag_front | F(θ)=Fsph+Fcyl·sin²(θ−axis)

👁

Visual Acuity Converter

Convert between Snellen, logMAR, decimal, and percentage visual acuity

Input

Enter VA Value

Format

logMAR 0.0 = 20/20 | logMAR 1.0 = 20/200 (legal blindness) | logMAR -0.1 = 20/16 (better than normal)

◱

Slab-Off / Differential Prism

Calculate differential vertical prism in downgaze and determine slab-off prescription

Prescriptions

OD Sphere (D)

OS Sphere (D)

Reading height below OC (mm)

Prentice's Rule: Δ = F × c (cm). Slab-off (bicentric grinding) neutralizes differential vertical prism in the reading position. Rule: apply to the MOST MINUS (or least plus) lens; adds Base-Up prism in the reading zone.

🔍

Spectacle Magnification

Calculate lens magnification from shape and power factors — and estimate aniseikonia between eyes

Single Lens Parameters

Back Vertex Power (D)

Front Base Curve (D)

Center Thickness (mm)

Refractive Index

Vertex Distance (mm)

Aniseikonia Estimate (optional)

OD Power (D)

OS Power (D)

SM = Shape Factor × Power Factor. SF = 1/(1 − t/n × F₁). PF = 1/(1 − d × F). Symptomatic aniseikonia typically ≥ 3–5% image size difference.

Contact Lens Database

100+ lenses including private labels. Click any row to expand full parameter details, axis charts, and store brand equivalents.

🔍 Prescription Search Find lenses that fit your Rx

Sphere (D)

Cylinder (D)

Axis (°)

Add Power

* Axes marked with * are only available in specialty/custom toric lenses. Standard soft torics offer axes in 10° increments: 10°, 20°, 70°-110°, 160°-180° for high minus/plus; all axes (10°-180°) for core powers.

Schedule:

Type:

Brand	Type	BC / Diam	Power Range

🔍

👁

Search or select a condition

Type in the search box, use the category filters, or click any condition from the list.

🧠

Optometry Quiz

NBEO / KMK / OptoPrep style

Topic:

🎯

All Topics

👁

Posterior Segment

🔬

Anterior Segment

📊

Glaucoma

🧬

Neuro-Ophthalm.

👀

Binocular Vision

📐

Refraction

💧

Contact Lenses

💊

Pharmacology

🌈

Color Vision

Difficulty:

🟢

Beginner

🟡

Intermediate

🔴

Advanced

Question 1 of 5

🔭

Optics & Dispensing

ABO / NOCE style

Topic:

🎯

All Topics

🔬

Ophthalmic Optics

👓

Dispensing

💧

Contact Lens Tech

💡 For BV, Refraction, Pharmacology — use the Optometry Quiz on the left.

Question 1 of 5

Landmark Clinical Trials

Key studies that define evidence-based optometry and ophthalmology practice · Most recent findings first within each category

Ocular Drug Reference

Searchable formulary organized by drug class · Mechanism, dosing, efficacy, side effects, contraindications

Clinical Normal Values

Reference ranges for ophthalmic measurements · Click any card to expand