1
Q
With movement seen in
A
Hypermetropia
Emmetropia
Myopia upto 1 D
Minus Lens (minify)
2
Q
Against movement seen in
A
Myopia >1D
3
Q
Deduction of distance
1 m
2/3 m
1/2 m
A
1D
1.5D
2D
4
Q
Deduction of Cycloplegic
Atropine
Homatropine
Cyclopentolate
A
1D
0.5D
0.75D
5
Q
Spherical equivalent is equal to
A
1/2 Cylinder
6
Q
What is the Pupillary Axis?
A
The line through the midpoint of the entrance pupil, perpendicular to the corneal surface.
7
Q
What is the Visual Axis?
A
The line connecting the fovea to the fixation target.
8
Q
What is the Optical Axis?
A
The line connecting the optical center of the cornea and the optical center of the crystalline lens.
9
Q
What is Angle Kappa (κ)?
A
The angle between the VISUSAL axis and the PUPPILARY axis.
KVP
10
Q
Significance ofAngle Kappa?
A
Anatomy, Macular Drag (FEVR).
Decentered LASIK ablations.
Positive angle simulates Exotropia.
Negative angle simulates Esotropia.
11
Q
What is Angle Alpha (α)?
A
The angle between the pupillary axis and the optical axis.
APO
12
Q
Significance of Angle Alpha?
A
Anatomy, Trauma, Surgery
A big angle makes a poor candidate for premium lenses (misalignment with optical elements).
13
Q
What is Angle Gamma (γ)?
A
The angle between the fixation axis and the optical axis.
G(t)FO
14
Q
Causes of abnormal Angle Gamma?
A
Anatomy, Trauma, Surgery.
15
Q
Define low vision.
A
A condition where, due to an irreversible visual disorder, a person cannot perform customary activities without special visual aids.
16
Q
What are the two main categories of Low Vision Aids (LVAs)?
A
- Optical LVAs
- Non-optical LVAs
17
Q
Enlist optical LVAs.
A
- Magnifying spectacles
- Hand magnifiers
- Stand magnifiers
- Telescopes
- Intraocular LVAs (telescopic IOLs, retinal prosthesis, etc.)
18
Q
Enlist non-optical LVAs.
A
- Approach magnification
- Lighting arrangements
- Contrast enhancement & glare reduction
- Linear magnification (large print, photocopies)
- Auditory aids
- Writing & communication devices
- Medical assistive devices
- Orientation & mobility aids
- Sensory substitution devices
- Technological LVAs (apps, e-readers, smartphones)
19
Q
What is the basic principle of optical LVAs?
A
With sufficient magnification, surrounding retina can be used for central vision by enlarging the image on the retina.
20
Q
What are basic features of optical LVAs?
A
Variable power, fixed/variable focus, may be illuminated or non-illuminated, monocular/binocular, uni/bifocal/trifocal.
21
Q
What is the optical principle of magnifying spectacles?
A
Magnification by convex lens is obtained by placing object within focal length → erect, virtual, magnified image formed.
22
Q
Advantages of magnifying spectacles.
A
Cosmetically acceptable, comfortable, hands free, stable fixation, simultaneous vision for near/distance, inexpensive.
23
Q
Disadvantages of magnifying spectacles.
A
Spherical aberrations (unless aspherical), short focal length → object very close, reduced illumination on reading matter.
24
Q
Indications of hand-held magnifiers.
A
For spot or short-time tasks in patients with field ≥10°; as auxiliary lens for finer tasks.
25
Advantages of hand magnifiers.
Greater working distance than spectacles, no need for accommodation, easy to manipulate eccentrically.
26
Disadvantages of hand magnifiers.
Hand not free, tiring, limited field of view, requires manual dexterity, must hold at correct distance.
27
Advantages of stand magnifiers.
Simple to use, useful in patients with hand tremors, self-illuminated designs available.
28
Disadvantages of stand magnifiers.
Small field of view, difficult if surface not flat, requires accommodative effort.
29
Enlist types of telescopes used in LVAs.
1. Galilean telescope
2. Keplerian telescope
3. Monocular or binocular
4. Hand-held or spectacle-mounted
5. Telescope Contact Lens
6. Intraocular Telescope
30
Advantages of telescopes.
Improves resolution of distant objects, useful for social/educational participation (TV, signs, blackboards).
31
Disadvantages of telescopes.
Restricted field, reduced illumination, difficulty in locating/focusing objects, limited depth of focus, cosmetic issues.
32
Enlist intraocular LVAs.
1. Implantable miniature telescope (IMT)
2. IOL-VIP system
3. Lipshitz macular implant
4. LMI-SI (sulcus-implanted)
5. iolAMD
6. Fresnel prism IOL
33
Examples of retinal prostheses.
1. Argus II epiretinal prosthesis
2. Alpha IMS subretinal implant
34
Enlist absorptive lenses used in LVAs.
1. Tinted lenses
2. Photochromatic lenses
3. Polarized lenses
4. Filters (yellow/amber, CPF, PLS)
35
Enlist visual field enhancement devices.
1. Fresnel prisms
2. Peli's expansion prisms
3. Hemianopic mirrors
4. Gottlieb field expanders
5. Reverse telescopes
36
Approach magnification - give example.
Encouraging patients to sit close to TV or screen.
37
What lighting is preferred for low vision patients?
Incandescent light (60–75W) preferred for continuous spectrum; varies by pathology (albinism needs low level, glaucoma needs high level).
38
Contrast enhancement methods in LVAs.
Typoscope
absorptive lenses, filters, black felt-tip pens, bold lines, contrasting backgrounds.
39
Enlist electronic magnifiers.
1. CCTV
2. Portable video magnifiers
3. Headborne electronic glasses
4. Large-print computers
5. Low Vision Imaging System (LVIS)
6. V-Max system
40
Advantages of CCTV over optical systems.
brighter
larger image
enhanced contrast
reverse polarity possible,
magnification up to 60X.
41
Limitations of CCTV.
Expensive, bulky, less portable, requires training to operate.
42
Enlist primary mobility aids.
Canes (long cane, identification cane, support cane, smart canes)
Guide dogs
43
What are secondary mobility aids?
1. Electronic orientation devices (ultrasonic sensors₹
2. GPS-based navigation
44
Enlist sensory substitution devices.
1. Talking books
2. Readers
3. Audio-descriptive devices
4. Braille paper displays
5. Non-Braille tactile outputs
45
Enlist technology-based LVAs.
1. E-readers/tablets (Kindle, iPad)
2. Smartphones with accessibility features
3. Apps like TapTapSee, Be My Eyes, Blindfold Games
4. Voice-activated assistants (Siri, Alexa, Google Assistant)
46
What are the two general styles of multifocal IOLs currently in vogue?
Refractive optics multifocal IOLs and Diffractive optics multifocal IOLs
47
What is the design of two-zone (bifocal) refractive multifocal IOLs?
Central near-vision segment (~2 mm) surrounded by a distance-vision segment
48
What is a disadvantage of two-zone refractive multifocal IOLs?
In bright sunlight, pupillary constriction blocks the distance segment, poorly tolerated for outdoor activities
49
What is the design of annulus type (bull’s-eye) refractive multifocal IOLs?
Central distance zone, surrounded by a near zone, then another distance zone, near and then distance
“DNDND”
50
What is a disadvantage of annulus type refractive multifocal IOLs?
Excessive pupillary constriction in bright light may block the near vision zone
51
What principle do diffractive multifocal IOLs use?
Wavefront optics and diffraction using microscopic steps between annuli
52
How is light distributed in diffractive multifocal IOLs?
Approx. 41% for near, 41% for distance, 18% lost
53
What are drawbacks of diffractive multifocal IOLs?
Reduced intermediate vision, glare, halos, reduced contrast sensitivity
54
What innovations improve diffractive IOLs?
Reduced height/spacing of diffractive rings, rounded edges, partial optic designs (e.g. ReSTOR), apodization
55
What is apodization in diffractive IOLs?
Gradual reduction in diffractive step height from center to periphery to improve intermediate vision
56
Give examples of diffractive multifocal IOLs.
ReSTOR (Alcon), TECNIS (AMO), Acri.LISA (Zeiss)
57
What is the major optical disadvantage of multifocal IOLs in general?
Reduced light intensity reaching the retina (about half the incoming light focused)
58
How do multifocal IOLs affect contrast sensitivity?
Decreased contrast sensitivity compared to monofocal IOLs due to reduced effective light
59
What are trifocal IOLs?
Newer lenses providing near, intermediate, and distance vision (e.g. PanOptix, Zeiss AT LISA Tri)
60
What is the AcrySof IQ PanOptix IOL?
Alcon trifocal IOL (FDA approved 2019), non-apodized design, ENLIGHTEN technology, adds: +2.17D intermediate, +3.25D near
61
What are higher-order aberrations (HOAs)?
Complex optical imperfections beyond myopia, hyperopia, and regular astigmatism; described by Zernike polynomials.
62
How are aberrations classified?
Lower-order (defocus, astigmatism) and Higher-order (coma, trefoil, spherical aberration, etc.).
63
Enlist the 3rd order higher-order aberrations.
Coma (horizontal/vertical), Trefoil.
64
Enlist the 4th order higher-order aberrations.
Spherical aberration, Quadrafoil, Secondary astigmatism.
65
Give examples of 5th order or higher HOAs.
More complex irregular patterns, clinically less significant.
66
What are the symptoms of HOAs?
Glare, halos, starbursts, reduced contrast sensitivity, poor night vision, ghosting.
67
Name common causes of HOAs.
Corneal irregularities (keratoconus, scars, post-LASIK), lens tilt/decentration, cataract, dry eye.
68
What is the gold standard method to measure HOAs?
Wavefront aberrometry (Hartmann–Shack, Tscherning, Ray tracing).
69
What does corneal topography measure in terms of aberrations?
Only corneal HOAs, not lenticular or total ocular HOAs.
70
What does double-pass retinal imaging measure?
Overall optical quality, including HOAs and scatter.
71
What are Zernike polynomials used for?
Mathematical representation of HOAs (e.g., coma, trefoil, spherical aberration).
72
How are HOAs quantified numerically?
As Root Mean Square (RMS) error in micrometers; higher RMS = worse optical quality.
73
How does the natural eye reduce HOAs?
Pupil constriction, corneal–lenticular compensation, symmetry of optics, neural adaptation.
74
What optical methods help reduce HOAs?
RGP or scleral lenses, wavefront-designed lenses, small aperture optics, miotics.
75
What surgical methods help manage HOAs?
Wavefront- or topo-guided LASIK/PRK, aspheric IOLs, ICRS, keratoplasty in advanced cases.
76
Define accommodation
Accommodation is the process by which the eye increases its dioptric power to focus near objects on the retina.
77
What is the physiological basis of accommodation?
It is mainly due to contraction of the ciliary muscle, which reduces zonular tension and allows the lens to become more convex.
78
Name the types of accommodation
1. Reflex accommodation, 2. Voluntary accommodation, 3. Proximal accommodation, 4. Convergence accommodation, 5. Tonic accommodation.
79
What is amplitude of accommodation?
It is the maximum increase in dioptric power the eye can achieve by accommodation.
80
How does amplitude of accommodation vary with age?
It decreases progressively with age, from about 14D in children to 0D at ~70 years (presbyopia).
81
What is near point of accommodation?
It is the nearest point at which the eye can see clearly with maximum accommodation exerted.
82
What is far point of accommodation?
It is the farthest point at which the eye can see clearly without any effort of accommodation.
83
Define range of accommodation
It is the distance between near point and far point of accommodation.
84
What is presbyopia?
Age-related decrease in amplitude of accommodation resulting in difficulty seeing near objects.
85
Causes of presbyopia
1. Age-related loss of lens elasticity, 2. Decreased ciliary muscle power, 3. Increased lens size.
86
Clinical features of presbyopia
Difficulty in near vision
need to hold objects farther away,
eye strain
and headache on near work.
Intermittent diplopia
87
Treatment of presbyopia
Convex lenses (reading glasses) to compensate for lost accommodation.
88
What is convergence accommodation?
Accommodation induced secondarily as a result of convergence of the eyes.
89
What is accommodative convergence?
Convergence that occurs in response to accommodation.
90
How to measure accommodative convergence/accommodation (AC/A) ratio?
By measuring amount of convergence (prism diopters) per diopter of accommodation.
91
What is accommodative insufficiency?
Condition where the amplitude of accommodation is less than expected for age.
92
What is accommodative excess?
Spasm of accommodation leading to difficulty in relaxation and blurred distance vision.
93
What is accommodative inertia?
Slowness of accommodation to shift from near to distance or vice versa.
94
Name tests for assessment of accommodation
1. Near point of accommodation test, 2. Push-up method, 3. Minus lens test, 4. Dynamic retinoscopy.
95
What is cycloplegia and its role in accommodation assessment?
Cycloplegia temporarily paralyses accommodation, allowing accurate measurement of refractive error in children and young adults.
96
What are the surgical treatment options for presbyopia?
1. Refractive corneal procedures
2. Lens-based procedures
3. Scleral procedures.
97
Name corneal procedures for presbyopia
Monovision LASIK,
PresbyLASIK (multifocal ablation),
Conductive keratoplasty
Corneal inlays.
98
What is monovision LASIK?
One eye corrected for distance, the other for near vision.
99
What is PresbyLASIK?
Excimer laser creates multifocal corneal surface to provide both near and distance vision.
100
What is conductive keratoplasty?
Uses radiofrequency energy to steepen the central cornea, temporarily improving near vision.
101
What are corneal inlays?
Small implants placed in corneal stroma to increase depth of focus (e.g., Kamra inlay).
102
Name lens-based surgical options for presbyopia
Multifocal intraocular lenses (IOLs),
Accommodating IOLs
Extended depth of focus (EDOF) IOLs.
Monovision
103
What are multifocal IOLs?
IOLs with concentric zones or diffractive optics to provide both distance and near vision.
104
What are accommodating IOLs?
IOLs designed to move or change shape in response to ciliary muscle contraction to restore accommodation.
105
What are EDOF IOLs?
Lenses that extend range of clear vision by elongating depth of focus, reducing need for reading glasses.
106
What are scleral surgical procedures for presbyopia?
Scleral expansion bands or implants to restore ciliary muscle efficiency and lens flexibility (less commonly used today).
107
Explain Helmholtz’s theory of accommodation
Ciliary muscle contraction reduces zonular tension → lens capsule elasticity makes the lens more convex → increases power for near vision.
108
Give the expected amplitude of accommodation at different ages
10 yrs: ~14 D, 20 yrs: ~10 D, 30 yrs: ~7 D, 40 yrs: ~4.5 D, 50 yrs: ~2.5 D, 60 yrs: ~1 D.
109
What are the causes of presbyopia?
1. Loss of lens elasticity, 2. Hardening of lens capsule, 3. Decreased ciliary muscle efficiency, 4. Increased lens size.
110
What are symptoms of presbyopia?
Difficulty reading small print, holding objects farther away, eye strain, headache, blurred near vision.
111
What is AC/A ratio?
The amount of accommodative convergence (in prism diopters) per diopter of accommodation.
112
How is AC/A ratio measured?
By gradient method using additional lenses, or heterophoria method.
113
What is tonic accommodation?
Baseline accommodation in absence of visual stimuli, usually about 1D.
114
What is reflex accommodation?
Involuntary accommodation in response to retinal blur.
115
What is voluntary accommodation?
Accommodation induced by conscious effort without blur stimulus.
116
What is proximal accommodation?
Accommodation stimulated by awareness of a near object, even without blur.
117
Treatment of accommodative insufficiency
Reading glasses or plus lenses for near work, accommodative facility exercises.
118
What is accommodative excess/spasm?
Condition with sustained accommodation, difficulty in relaxation → blurred distance vision, pseudomyopia.
119
Treatment of accommodative excess
Cycloplegic drops, plus lenses for near, vision therapy.
120
What is accommodative inertia (ill-sustained accommodation)?
Sluggishness or fatigue of accommodation → difficulty in sustaining near focus.
121
Treatment of accommodative inertia
Near vision glasses, accommodative facility training.
122
Describe the push-up method for accommodation
A near target is moved closer until the patient reports blur → distance from eye gives near point.
123
Describe the minus lens method for accommodation
Minus lenses are added in front of the eye until sustained blur occurs → measures amplitude.
124
Describe dynamic retinoscopy
Objective assessment by observing retinoscopic reflex as patient focuses on a near target.
125
List drugs used for cycloplegia
Atropine, Cyclopentolate, Homatropine, Tropicamide.
126
What is paralysis of accommodation (cycloplegia)?
Complete loss of accommodation due to ciliary muscle paralysis, e.g., drugs, trauma, neuropathy.
127
What is spasm of accommodation?
Excessive involuntary contraction of ciliary muscle → pseudomyopia and asthenopia.
128
List causes of spasm of accommodation
1. Prolonged near work, 2. Head injury, 3. Intracranial lesions, 4. Ocular inflammation.
129
Treatment of spasm of accommodation
Cycloplegics, bifocals, plus lenses, vision therapy, treating underlying cause.
130
What is presbyopic correction add power at 40 yrs?
About +1.0 D to +1.25 D.
131
What is presbyopic correction add power at 50 yrs?
About +2.0 D.
132
What is presbyopic correction add power at 60 yrs?
About +3.0 D.
Eye
flashcards
Decks in class (23)
# Cards
-
Glaucoma46
-
Proptosis3
-
Lasers In Glaucoma9
-
Cataract102
-
Glaucoma 25
-
Trials In Glaucoma19
-
TRON3
-
Orbit21
-
Uveitis21
-
Squint80
-
Eyelids114
-
Glaucoma Surgery87
-
Corneal Ulcer35
-
Primary Congenital Glaucoma7
-
Miscellaneous37
-
Cornea95
-
Neuro-ophthalmology129
-
Optics132
-
Injury34
-
Retina144
-
Retina Anatomy24
-
Lens Anatomy7
-
Dry Eye32
