Presbyopia & Multifocal Contact Lenses: Complete NCLE Guide

Your patient hits 43 and suddenly can't read the menu at restaurants. They hold their phone at arm's length. They're squinting at text messages. Welcome to presbyopia—the age-related loss of near focusing ability that affects literally everyone who lives long enough. And here's the thing: the presbyopic contact lens market is exploding. Baby boomers want to stay active, and they don't want readers hanging from their necks.

The NCLE knows presbyopia is huge. You'll see 25+ questions about what causes it (spoiler: it's not the ciliary muscle), how to correct it with contact lenses—monovision, simultaneous vision multifocals, center-near vs center-distance designs—and most critically, which patients are good candidates and which will never adapt. This isn't optional knowledge. Presbyopes are your growth demographic.

In this guide, you'll learn exactly what presbyopia is and what causes it (lens stiffening, not muscle weakness), monovision fitting philosophy and patient selection, simultaneous vision multifocal designs (center-near vs center-distance), add power selection for different ages, and troubleshooting when things don't work. By the end, you'll know how to fit that 45-year-old who insists they want contact lenses but can't see their computer anymore.

Definition

Presbyopia is the age-related loss of accommodation—the eye's ability to focus on near objects. It's not a disease, not a refractive error, and not something you can prevent. It's a normal physiological change that starts around age 40-45 and progresses until about age 60-65.

The Real Cause (Not What Most People Think)

Here's the #1 misconception that shows up on NCLE exams: Presbyopia is NOT caused by weakening of the ciliary muscle. The ciliary muscle function remains intact throughout life. You can prove this by putting a drop of pilocarpine (which stimulates the ciliary muscle) in a presbyopic eye—the muscle contracts just fine, but accommodation still doesn't happen.

The actual cause: The crystalline lens loses elasticity with age. The lens grows throughout life, adding new layers like tree rings. As it gets bigger and denser, it becomes stiffer. The ciliary muscle can still contract, but the lens can no longer change shape in response. It's like trying to squeeze a hard rubber ball—your hand is strong, but the ball won't deform.

Amplitude of Accommodation

Amplitude of accommodation is the maximum amount the eye can focus up close, measured in diopters. It decreases predictably with age.

Symptoms

Patients typically notice these symptoms starting around age 40-45:

• Difficulty reading small print—the hallmark symptom
• Holding reading material farther away—"my arms aren't long enough anymore"
• Eye strain with near work—especially prolonged reading or computer use
• Headaches—from straining to focus
• Symptoms worse in dim lighting—pupils dilate in dim light, reducing depth of focus
• Symptoms worse when tired—end-of-day near vision difficulty
• Need brighter light for reading

What Presbyopia is NOT

Presbyopia is not:

• Hyperopia—that's a refractive error present from birth (though hyperopes notice presbyopia earlier)
• Affecting only one eye—presbyopia is bilateral. If only one eye has near vision problems, it's something else
• Sudden onset—it's gradual, not overnight. Sudden near vision loss suggests a medical issue
• Preventable—everyone gets it eventually. Eye exercises don't prevent presbyopia (no matter what the internet says)

Concept

Monovision is the most common contact lens correction for presbyopia. The concept is elegantly simple:

• Distance eye: Typically the dominant eye, corrected for distance vision (full distance Rx)
• Near eye: Typically the non-dominant eye, corrected for near vision (add plus power to the distance Rx)
• Brain adaptation: The brain learns to select the appropriate eye for each task—distance eye for driving, near eye for reading

It's not perfect—you're compromising binocular vision—but success rates are 60-80% with proper patient selection.

Determining Eye Dominance

Before fitting monovision, you need to determine which eye is dominant. Most common methods:

General rule: About 65% of people are right-eye dominant, 35% left-eye dominant. Dominance doesn't always match handedness.

Typical Monovision Prescription

Distance eye: Full distance correction
Near eye: Distance correction + add power

Typical add: Start with +1.50D. Increase to +2.00 or +2.50 if needed for better near vision. Don't go higher than +2.50—beyond that, distance eye can't compensate well.

Advantages of Monovision

• Simple to fit—uses standard single vision lenses
• Works with any lens type—soft, RGP, toric lenses
• Lower cost—no special multifocal lenses required
• Good success rate—60-80% of properly selected patients adapt
• Can be used with astigmatism correction—toric monovision is common

Disadvantages of Monovision

• Reduced binocular vision—you're deliberately creating anisometropia
• Decreased depth perception—stereoacuity is reduced (relies on binocular vision)
• Adaptation required—most patients need 1-2 weeks to adjust
• May affect night driving—distance eye performance can be slightly reduced in low light
• Not suitable for everyone—some patients can't tolerate the compromise

Patient Selection for Monovision

Modified Monovision

A variation that gives better intermediate vision:

• Distance eye: Single vision lens for distance (unchanged)
• Near eye: Multifocal lens (provides both near and some distance)

This provides better intermediate vision (computer work) and less compromise than full monovision. It's a nice middle ground for patients who struggle with traditional monovision.

Concept

Simultaneous vision multifocals have both distance and near zones in each lens. Both images reach the retina at the same time, and the brain learns to suppress the unwanted image and pay attention to the appropriate one.

Think of it like this: When you look at distance, the distance zone provides a clear image and the near zone provides a blurry image. Your brain ignores the blur and focuses on the clear distance image. When you look at near, the reverse happens.

This is more challenging than monovision (both eyes see blur simultaneously), but the advantage is better binocular vision and depth perception.

Center-Near Design

How it works:

• Small pupil (bright light): Near zone is dominant because pupil is small and only the center is used. Good for reading in bright light.
• Large pupil (dim light): Both zones contribute. Distance zone (periphery) also receives light. Balance shifts toward distance, but near is still available.

Best for:

• Patients prioritizing reading/near work
• Low myopes
• Office workers (computer and paperwork)
• Patients who do most near work in good lighting

Center-Distance Design

How it works:

• Small pupil (bright light): Distance zone is dominant. Excellent distance vision in bright conditions.
• Large pupil (dim light): Near zone (periphery) also contributes. Some distance compromise in low light, but better than center-near for distance-critical tasks.

Best for:

• Patients prioritizing distance vision
• Hyperopes
• Drivers (better distance vision at night)
• Active patients who want good distance for sports/activities

Aspheric vs Concentric Designs

Add Power Selection

Multifocal lenses come in different add powers. Selection is typically based on age and near vision needs:

Fitting tip: Start with a low add and increase as needed. It's easier to increase add power than decrease it. Patients adapt better to gradual increases.

Advantages of Simultaneous Vision Multifocals

• Better binocular vision than monovision—both eyes contribute to distance and near
• Less compromise of depth perception—maintains better stereopsis
• Good for critical vision tasks—pilots, surgeons who can't use monovision
• Better intermediate vision—especially with aspheric designs

Disadvantages of Simultaneous Vision Multifocals

• More difficult adaptation—brain must learn to suppress blur from unwanted zone
• Reduced contrast sensitivity—both distance and near images are present, reducing overall clarity
• Glare and halos—especially at night with lights. This is common and may not improve.
• More expensive—specialized lens designs cost more
• Not everyone can adapt—10-20% of patients can't tolerate the simultaneous blur
• May need different add powers OD vs OS—fine-tuning can be complex

Alternating vision designs are RGP-only and work like bifocal spectacles:

• Top portion: Distance correction
• Bottom portion: Near correction (segment with add power)
• Lower lid holds lens in position
• Gaze shifts up for distance, down for near

Design: The lens has a flat bottom (truncation) or prism ballast to maintain orientation. The near segment is at the bottom, like a bifocal. When you look down to read, the lens translates (moves up on the eye) so the near segment aligns with your line of sight.

Success factors:

• Requires good lower lid support (lid must hold lens in place)
• Larger palpebral aperture (opening between lids)
• Patient must have appropriate lid anatomy

Reality: Alternating vision RGPs are less common today. Most fitters prefer simultaneous vision designs or monovision. Success rates are lower, and fitting is more challenging.

Initial Fitting Process

1. Determine distance Rx accurately—start with perfect distance correction
2. Determine add power needed—use near point test or age-based guidelines
3. Select lens design—center-near vs center-distance based on patient priorities
4. Fit for distance vision first—ensure distance Rx is correct
5. Assess near vision—check reading ability at 14-16 inches
6. Refine as needed—adjust add power or design if necessary
7. Allow adaptation period—1-2 weeks minimum before giving up

Troubleshooting Common Problems

Setting Realistic Expectations

This is critical for success. Before fitting, tell patients:

• Vision won't be as good as spectacles—it's a compromise
• All distances will be somewhat compromised—no perfect distance or near
• Adaptation takes 1-2 weeks—don't judge immediately
• Night vision may be affected—glare and halos are common
• Some patients never adapt—10-20% failure rate even with proper selection
• May need reading glasses for extended reading—especially fine print

If you promise perfect vision, you'll have unhappy patients. If you set realistic expectations, most patients will be satisfied with the compromise.

• Patient motivation—this is #1. Motivated patients adapt; unmotivated patients fail
• Realistic expectations—patients who understand the compromise succeed
• Adequate trial period—2 weeks minimum before deciding it won't work
• Appropriate design selection—center-near vs center-distance matters
• Starting with low adds—easier to add power than reduce
• Follow-up visits—check in at 1 week, 2 weeks, 1 month
• Willingness to try different options—monovision, modified monovision, different multifocal designs

• Cause of presbyopia: Lens loses elasticity (NOT ciliary muscle weakness)
• Typical age of onset: 40-45 years
• Monovision setup: Dominant eye for distance, non-dominant eye for near
• Center-near vs center-distance: Center-near better for reading, center-distance better for distance/driving
• Simultaneous vision concept: Both distance and near zones present in each lens; brain suppresses unwanted image
• Add power ranges: Low (+0.75-1.50), Medium (+1.75-2.25), High (+2.50-3.00)
• Monovision advantages: Simple, lower cost, good success rate
• Monovision disadvantages: Reduced depth perception, not for pilots/surgeons