SlideShare une entreprise Scribd logo
1  sur  26
Télécharger pour lire hors ligne
ANISEIKONIA
 A condition wherein the images projected to the
visual cortex from the two retinae are abnormally
unequal in size and/or shape.
 Up to 5% - well tolerated.
Symptoms
• 1. Asthenopia, i.e., eyeache, browache and tiredness
• of eyes.
• 2. Diplopia due to difficult binocular vision when
• the difference in images of two eyes is more than
• 5 percent
• 3. Difficulty in depth perception.
Etiological types
Optical aniseikonia
• may occur due to
either inherent or
acquired
anisometropia of
high degree.
Retinal aniseikonia
• may develop due
to: displacement
of retinal
elements towards
the nodal point in
one eye due to
stretching or
oedema of the
retina.
Cortical aniseikonia
• implies
asymmetrical
simultaneous
perception inspite
of equal size of
images formed on
the two retinae.
Clinical types
a) Spherical - magnified or
minified equally in both
meridia
b) Cylindrical - magnified or
minified symmetrically in one
meridian .
a) Prismatic - image difference
increases progressively in one
direction
b) Pincushion - image distortion
increases progressively in both
directions, as seen with high plus
correction in aphakia
c) Barrel distortion - image distortion
decreases progressively in both
directions, as seen with high minus
correction
d) Oblique distortion- size of image is
same, but oblique distortion of
shape
• 1. Symmetrical aniseikonia • 2. Asymetrical aniseikonia
Treatment
• 1. Optical aniseikonia may be corrected by
• aniseikonic glasses, contact lenses or intraocular
• lenses depending upon the situation.
• 2. For retinal aniseikonia treat the cause.
• 3. Cortical aniseikonia is very difficult to treat.
APHAKIA
‘Absence of crystalline lens’ from the eye
Optical point of view – condition in which lens is absent from
the pupillary area
Produces high degree hypermetropia
Aniseikonia [ophthalmology description for medical students ]
Causes
1. Congenital absence of lens
2. Surgical aphakia
3. Aphakia due to absorption of lens matter
4. Trauma extrusion of lens
5. Posterior dislocation of lens
Optical changes in the eye after
removal of crystalline lens
• High degree hypermetropia
• Total power of eye is reduced from +60D to about +44D
• Anterior focal point becomes 23.2 mm in front of the cornea ( N : 15.7 mm )
• Posterior focal point is about 7mm behind the eyeball i.e 31mm behind the cornea
• Accommodation is lost completely
Clinical features
SYMPTOMS –
• Defective vision : for both far and near
• Erythropsia and cyanopsia
SIGNS –
• Limbal scar
• Anterior chamber deeper than normal
• Iridodonesis
• Pupil is jet black in colour
• Purkinje image test shows only two images
• Fundus examination shows hypermetrophic small
disc
• Retinoscopy and autorefractometry reveals high
hypermetropia
Treatment
 Spectacles –
 +10D with cylindrical lenses for surgically induced astigmatism in previously emmetropic
patients
 An addition of +3 to +4 D is required for near vision to compensate for loss of accommodation.
 Contact lens
 IOL Implantation
o Primary IOL implantation- during cataract surgery
o Secondary IOL implantation- already aphakic patients
 Refractive corneal surgery
o Keratophakia, Epikeratophakia, Hyperopic LASIK
 Keratophakia. In this
procedure a lenticule
prepared from the donor
cornea is placed between the
lamellae of patient's cornea.
 Epikeratophakia. In this
procedure, the lenticule
prepared from the donor
cornea is stitched over the
surface of cornea after
removing the epithelium.
 Hyperopic Lasik
Anisometropia
Condition where total refraction of two eyes is
unequal
degree of
anisometropia
difference in size of
two retinal images
1 D 2 % No concern
2.5 D 5 % Well tolerated
2.5 D to 4 D can be tolerated
depending upon the
individual sensitivity
> 4 D not tolerated
Matter of concern
ETIOLOGY –
1.Congenital and developmental anisometropia
- due to differential growth of eyeballs
2.Acquired anisometropia
- asymmetric age change
- removal of cataractous lens
- implantation of IOL of wrong power
CLINICAL TYPES –
1.Simple anisometropia
- Simple myopic anisometropia
- Simple hypermetropic anisometropia
2. Compound anisometropia
- Compound myopic anisometropia
- Compound hypermetropic anisometropia
3.Mixed anisometropia / antimetropia
4.Simple astigmatic anisometropia
5.Compound astigmatic anisometropia
STATUS OF VISION IN ANISOMETROPIA –
1.Small degree anisometropia – Binocular vision
2.When refractive error in one eye is of high degree –
Uniocular vision
3.When one eye is hypermetropic and the other is
myopic – Alternate vision
DIAGNOSIS –
• Retinoscopic examination
• Autorefractometry
TREATMENT –
1.Spectacles
2.Contact lenses
3.IOL implantation
4.Refractive corneal surgery
5.Phakic refractive lenses ( PRL )
6.Refractive lens exchange ( RLE )
Aniseikonia [ophthalmology description for medical students ]
Astigmatism
• Type of refractive error wherein the refraction varies in
the different meridian.
• Consequently, the rays of light entering in the eye cannot
converge to a point focus but form focal lines
Regular
BASED ON
ETIOLOGY
1. Corneal
astigmatism
2. Lenticular
astigmatism
i. Curvatural
Eg.lenticonus
ii. Positional
Eg. subluxation.
iii. Index.
3. Retinal
astigmatism
Depending upon
the axis and the
angle between the
two principal
meridia
1. With-the-rule
astigmatism
2. Against-the-rule
astigmatism
3. Oblique
astigmatism
4. Bioblique
astigmatism
Depending upon
the position of the
two focal lines in
relation to retina
Simple
astigmatism,
Compound
astigmatism
Mixed astigmatism
• Symptoms
Defective vision;
blurring of objects;
(iii) depending upon the type and degree of
astigmatism, objects may
appear proportionately elongated; and
(iv) asthenopic symptoms, which are marked
especially in small
amount of astigmatism, consist of a dull ache in the
eyes, headache, early tiredness of eyes and
sometimes nausea and even drowsiness.
• Signs
• 1. Different power in two meridia is revealed on
• retinoscopy or autorefractometry.
• 2. Oval or tilted optic disc may be seen on
• ophthalmoscopy in patients with high degree of
• astigmatism.
• 3. Head tilt. The astigmatic patients may (very
• exceptionally) develop a torticollis in an
attempt
• to bring their axes nearer to the horizontal or
• vertical meridians.
• 4. Half closure of the lid. Like myopes, the
astigmatic
• patients may half shut the eyes to achieve the
• greater clarity of stenopaeic vision.
Treatment
• 1. Optical treatment
• i. Spectacles with full correction of cylindrical power and appropriate axis should be used for
distance and near vision.
• ii. Contact lenses. Rigid contact lenses may correct upto 2-3 of regular astigmatism, while
soft contact lenses can correct only little astigmatism. For higher degrees of astigmatism toric
contact lenses are needed. In order to maintain the correct axis of toric lenses, ballasting or
truncation is required.
• 2. Surgical correction
IRREGULAR ASTIGMATISM
• It is characterized by an irregular change of refractive power in different meridia. There
are multiple meridian which admit no geometrical analysis.
• Etiological types
• 1. Curvatural irregular astigmatism is found in patients with extensive corneal scars or
keratoconus.
• 2. Index irregular astigmatism due to variable refractive index in different parts of the
crystalline lens may occur rarely during maturation of cataract.
• Symptoms of irregular astigmatism include:
• _ Defective vision,
• _ Distortion of objects and
• _ Polyopia.
• Investigations
• 1. Placido's disc test reveales distorted circles
• 2. Photokerotoscopy and computerized corneal topography give photographic record of
irregular corneal curvature.
• Treatment
1. Optical treatment - contact lens
2. Phototherapeutic keratectomy (PTK)
3. Surgical treatment is indicated in extensivecorneal and consists of penetrating keratoplasty.
Refractive surgery for astigmatism
• Refractive surgical techniques employed for myopia can be adapted to correct
astigmatism alone or simultaneously with myopia as follows:
• 1. Astigmatic keratotomy (AK) refers to makingtransverse cuts in the mid periphery of
the steep corneal meridian
• 2. Photo-astigmatic refractive keratotomy (PARK)
• 3. LASIK to correctastigmatism upto 5D.
• Management of post-keratoplasty astigmatism
• 1. Selective removal of sutures in steep meridians

Contenu connexe

Tendances

Refraction in different refractive errors and their Management
Refraction in different refractive errors and their ManagementRefraction in different refractive errors and their Management
Refraction in different refractive errors and their ManagementDrArvindMorya
 
High myopia and management
High myopia and managementHigh myopia and management
High myopia and managementsabina paudel
 
Refraction 1 k n jha, 24.08.16
Refraction  1 k n jha, 24.08.16Refraction  1 k n jha, 24.08.16
Refraction 1 k n jha, 24.08.16ophthalmgmcri
 
Refractive error and conjuctivitis for nursing
 Refractive error and conjuctivitis for nursing Refractive error and conjuctivitis for nursing
Refractive error and conjuctivitis for nursingAmrit Jeetla
 
Refrective errors of eyes
Refrective errors of eyesRefrective errors of eyes
Refrective errors of eyesRaghu Veer
 
Myopia refractive error-M.B
Myopia refractive error-M.BMyopia refractive error-M.B
Myopia refractive error-M.BMeenank Bheeshva
 
Binocular Single Vision Tests
Binocular Single Vision TestsBinocular Single Vision Tests
Binocular Single Vision TestsRabia Ammer
 
Refractiveerrors 130309052054-phpapp01
Refractiveerrors 130309052054-phpapp01Refractiveerrors 130309052054-phpapp01
Refractiveerrors 130309052054-phpapp01Amarjeet Sinha
 
MYOPIA A REFRACTIVE ERROR OF AN EYE
MYOPIA A REFRACTIVE ERROR OF AN EYEMYOPIA A REFRACTIVE ERROR OF AN EYE
MYOPIA A REFRACTIVE ERROR OF AN EYEAyushiPatel59
 
Hypermetropia also known as Hyperopia or Farsightedness is a common type of r...
Hypermetropia also known as Hyperopia or Farsightedness is a common type of r...Hypermetropia also known as Hyperopia or Farsightedness is a common type of r...
Hypermetropia also known as Hyperopia or Farsightedness is a common type of r...Khagendra Shrestha
 
Iridocorneal endothelial syndrome
Iridocorneal endothelial syndromeIridocorneal endothelial syndrome
Iridocorneal endothelial syndromeSSSIHMS-PG
 
Hypermetropia ppt
Hypermetropia pptHypermetropia ppt
Hypermetropia pptavinas
 

Tendances (20)

Myopia
MyopiaMyopia
Myopia
 
Refraction in different refractive errors and their Management
Refraction in different refractive errors and their ManagementRefraction in different refractive errors and their Management
Refraction in different refractive errors and their Management
 
High myopia and management
High myopia and managementHigh myopia and management
High myopia and management
 
Refraction 1 k n jha, 24.08.16
Refraction  1 k n jha, 24.08.16Refraction  1 k n jha, 24.08.16
Refraction 1 k n jha, 24.08.16
 
Refraction and refractive errors
Refraction and refractive errorsRefraction and refractive errors
Refraction and refractive errors
 
Aniseikonia
AniseikoniaAniseikonia
Aniseikonia
 
Astigmatism
AstigmatismAstigmatism
Astigmatism
 
Refractive error and conjuctivitis for nursing
 Refractive error and conjuctivitis for nursing Refractive error and conjuctivitis for nursing
Refractive error and conjuctivitis for nursing
 
Refrective errors of eyes
Refrective errors of eyesRefrective errors of eyes
Refrective errors of eyes
 
Myopia refractive error-M.B
Myopia refractive error-M.BMyopia refractive error-M.B
Myopia refractive error-M.B
 
Anisometropia
Anisometropia Anisometropia
Anisometropia
 
Errors of refraction
Errors of refraction Errors of refraction
Errors of refraction
 
Refractive error
Refractive errorRefractive error
Refractive error
 
Error of Refraction
Error of RefractionError of Refraction
Error of Refraction
 
Binocular Single Vision Tests
Binocular Single Vision TestsBinocular Single Vision Tests
Binocular Single Vision Tests
 
Refractiveerrors 130309052054-phpapp01
Refractiveerrors 130309052054-phpapp01Refractiveerrors 130309052054-phpapp01
Refractiveerrors 130309052054-phpapp01
 
MYOPIA A REFRACTIVE ERROR OF AN EYE
MYOPIA A REFRACTIVE ERROR OF AN EYEMYOPIA A REFRACTIVE ERROR OF AN EYE
MYOPIA A REFRACTIVE ERROR OF AN EYE
 
Hypermetropia also known as Hyperopia or Farsightedness is a common type of r...
Hypermetropia also known as Hyperopia or Farsightedness is a common type of r...Hypermetropia also known as Hyperopia or Farsightedness is a common type of r...
Hypermetropia also known as Hyperopia or Farsightedness is a common type of r...
 
Iridocorneal endothelial syndrome
Iridocorneal endothelial syndromeIridocorneal endothelial syndrome
Iridocorneal endothelial syndrome
 
Hypermetropia ppt
Hypermetropia pptHypermetropia ppt
Hypermetropia ppt
 

Similaire à Aniseikonia [ophthalmology description for medical students ]

Myopia lecture By Sumayya Naseem
Myopia lecture By Sumayya NaseemMyopia lecture By Sumayya Naseem
Myopia lecture By Sumayya NaseemSumayya Naseem
 
optics.Dr.Mutaz.ppt
optics.Dr.Mutaz.pptoptics.Dr.Mutaz.ppt
optics.Dr.Mutaz.pptAdel930879
 
Refractive errors (eye condions)
Refractive errors (eye condions)Refractive errors (eye condions)
Refractive errors (eye condions)NehaNupur8
 
Myopia Ophthalmology ( Quick Review )
Myopia Ophthalmology ( Quick Review )Myopia Ophthalmology ( Quick Review )
Myopia Ophthalmology ( Quick Review )Priyanka Mishra
 
Reffraction myopia by Dr Abdul Basir safi eye surgeon from Afghanistan
Reffraction myopia by Dr Abdul Basir safi eye surgeon from AfghanistanReffraction myopia by Dr Abdul Basir safi eye surgeon from Afghanistan
Reffraction myopia by Dr Abdul Basir safi eye surgeon from AfghanistanDr Abdul Basir Safi
 
OPHTHALMOLOGY PRESENTATION, TOPIC ON MYOPIA
OPHTHALMOLOGY PRESENTATION, TOPIC ON MYOPIAOPHTHALMOLOGY PRESENTATION, TOPIC ON MYOPIA
OPHTHALMOLOGY PRESENTATION, TOPIC ON MYOPIAkadayathsandeep
 
11. Refractive errors.pptx
11. Refractive errors.pptx11. Refractive errors.pptx
11. Refractive errors.pptxAnnie Amjad
 
11. Refractive errors.pptx
11. Refractive errors.pptx11. Refractive errors.pptx
11. Refractive errors.pptxannieamjad1
 
Optics of ametropia
Optics of ametropiaOptics of ametropia
Optics of ametropiaSSSIHMS-PG
 
Accommodation and convergence
Accommodation and convergenceAccommodation and convergence
Accommodation and convergenceSAMEEKSHA AGRAWAL
 
Adaptive mechanism of squint
Adaptive mechanism of squintAdaptive mechanism of squint
Adaptive mechanism of squintOm Patel
 

Similaire à Aniseikonia [ophthalmology description for medical students ] (20)

MYOPIA.pptx
MYOPIA.pptxMYOPIA.pptx
MYOPIA.pptx
 
Myopia lecture By Sumayya Naseem
Myopia lecture By Sumayya NaseemMyopia lecture By Sumayya Naseem
Myopia lecture By Sumayya Naseem
 
optics.Dr.Mutaz.ppt
optics.Dr.Mutaz.pptoptics.Dr.Mutaz.ppt
optics.Dr.Mutaz.ppt
 
Aphakia
AphakiaAphakia
Aphakia
 
Refractive errors (eye condions)
Refractive errors (eye condions)Refractive errors (eye condions)
Refractive errors (eye condions)
 
Myopia Ophthalmology ( Quick Review )
Myopia Ophthalmology ( Quick Review )Myopia Ophthalmology ( Quick Review )
Myopia Ophthalmology ( Quick Review )
 
Reffraction myopia by Dr Abdul Basir safi eye surgeon from Afghanistan
Reffraction myopia by Dr Abdul Basir safi eye surgeon from AfghanistanReffraction myopia by Dr Abdul Basir safi eye surgeon from Afghanistan
Reffraction myopia by Dr Abdul Basir safi eye surgeon from Afghanistan
 
Hypermetropia
HypermetropiaHypermetropia
Hypermetropia
 
Refraction-II.pptx
Refraction-II.pptxRefraction-II.pptx
Refraction-II.pptx
 
strabismus.pptx
strabismus.pptxstrabismus.pptx
strabismus.pptx
 
Refractive errors
Refractive errorsRefractive errors
Refractive errors
 
OPHTHALMOLOGY PRESENTATION, TOPIC ON MYOPIA
OPHTHALMOLOGY PRESENTATION, TOPIC ON MYOPIAOPHTHALMOLOGY PRESENTATION, TOPIC ON MYOPIA
OPHTHALMOLOGY PRESENTATION, TOPIC ON MYOPIA
 
Anisometropia
AnisometropiaAnisometropia
Anisometropia
 
11. Refractive errors.pptx
11. Refractive errors.pptx11. Refractive errors.pptx
11. Refractive errors.pptx
 
11. Refractive errors.pptx
11. Refractive errors.pptx11. Refractive errors.pptx
11. Refractive errors.pptx
 
Aniso saiful
Aniso saifulAniso saiful
Aniso saiful
 
Optics of ametropia
Optics of ametropiaOptics of ametropia
Optics of ametropia
 
Refraction-I.ppt
Refraction-I.pptRefraction-I.ppt
Refraction-I.ppt
 
Accommodation and convergence
Accommodation and convergenceAccommodation and convergence
Accommodation and convergence
 
Adaptive mechanism of squint
Adaptive mechanism of squintAdaptive mechanism of squint
Adaptive mechanism of squint
 

Dernier

Male Infertility, Antioxidants and Beyond
Male Infertility, Antioxidants and BeyondMale Infertility, Antioxidants and Beyond
Male Infertility, Antioxidants and BeyondSujoy Dasgupta
 
High-Performance Thin-Layer Chromatography (HPTLC)
High-Performance Thin-Layer Chromatography (HPTLC)High-Performance Thin-Layer Chromatography (HPTLC)
High-Performance Thin-Layer Chromatography (HPTLC)kishan singh tomar
 
A presentation on Thermal gravimetry analysis (TGA)
A presentation on Thermal gravimetry analysis (TGA)A presentation on Thermal gravimetry analysis (TGA)
A presentation on Thermal gravimetry analysis (TGA)1922Jaygohel
 
Forensic Nursing powerpoint presentation
Forensic Nursing powerpoint presentationForensic Nursing powerpoint presentation
Forensic Nursing powerpoint presentationKavitha Krishnan
 
Arthroscopic Surgery in Indore : A Minimally Invasive Guide to Joint Health
Arthroscopic Surgery in Indore : A Minimally Invasive Guide to Joint HealthArthroscopic Surgery in Indore : A Minimally Invasive Guide to Joint Health
Arthroscopic Surgery in Indore : A Minimally Invasive Guide to Joint HealthGokuldas Hospital
 
AI in Action: Elevating Patient Insights
AI in Action: Elevating Patient InsightsAI in Action: Elevating Patient Insights
AI in Action: Elevating Patient InsightsEmily Kunka, MS, CCRP
 
MedMatch: Your Health, Our Mission. Pitch deck.
MedMatch: Your Health, Our Mission. Pitch deck.MedMatch: Your Health, Our Mission. Pitch deck.
MedMatch: Your Health, Our Mission. Pitch deck.whalesdesign
 
Role of Soap based and synthetic or syndets bar
Role of  Soap based and synthetic or syndets barRole of  Soap based and synthetic or syndets bar
Role of Soap based and synthetic or syndets barmohitRahangdale
 
Transport across cell membrane (passive, active, vesicular)
Transport across cell membrane (passive, active, vesicular)Transport across cell membrane (passive, active, vesicular)
Transport across cell membrane (passive, active, vesicular)MedicoseAcademics
 
Male Infertility Panel Discussion by Dr Sujoy Dasgupta
Male Infertility Panel Discussion by Dr Sujoy DasguptaMale Infertility Panel Discussion by Dr Sujoy Dasgupta
Male Infertility Panel Discussion by Dr Sujoy DasguptaSujoy Dasgupta
 
Pharmacokinetic Models by Dr. Ram D. Bawankar.ppt
Pharmacokinetic Models by Dr. Ram D.  Bawankar.pptPharmacokinetic Models by Dr. Ram D.  Bawankar.ppt
Pharmacokinetic Models by Dr. Ram D. Bawankar.pptRamDBawankar1
 
Cure of patients which terminally ill.pdf
Cure of patients which terminally ill.pdfCure of patients which terminally ill.pdf
Cure of patients which terminally ill.pdfrg0000009
 
DNA nucleotides Blast in NCBI and Phylogeny using MEGA Xi.pptx
DNA nucleotides Blast in NCBI and Phylogeny using MEGA Xi.pptxDNA nucleotides Blast in NCBI and Phylogeny using MEGA Xi.pptx
DNA nucleotides Blast in NCBI and Phylogeny using MEGA Xi.pptxMAsifAhmad
 
PAIN/CLASSIFICATION AND MANAGEMENT OF PAIN.pdf
PAIN/CLASSIFICATION AND MANAGEMENT OF PAIN.pdfPAIN/CLASSIFICATION AND MANAGEMENT OF PAIN.pdf
PAIN/CLASSIFICATION AND MANAGEMENT OF PAIN.pdfDolisha Warbi
 
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.aarjukhadka22
 
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA .pdf
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA    .pdfSGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA    .pdf
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA .pdfHongBiThi1
 
Generative AI in Health Care a scoping review and a persoanl experience.
Generative AI in Health Care a scoping review and a persoanl experience.Generative AI in Health Care a scoping review and a persoanl experience.
Generative AI in Health Care a scoping review and a persoanl experience.Vaikunthan Rajaratnam
 

Dernier (20)

Male Infertility, Antioxidants and Beyond
Male Infertility, Antioxidants and BeyondMale Infertility, Antioxidants and Beyond
Male Infertility, Antioxidants and Beyond
 
High-Performance Thin-Layer Chromatography (HPTLC)
High-Performance Thin-Layer Chromatography (HPTLC)High-Performance Thin-Layer Chromatography (HPTLC)
High-Performance Thin-Layer Chromatography (HPTLC)
 
A presentation on Thermal gravimetry analysis (TGA)
A presentation on Thermal gravimetry analysis (TGA)A presentation on Thermal gravimetry analysis (TGA)
A presentation on Thermal gravimetry analysis (TGA)
 
Biologic therapy ice breaking in rheumatology, Case based approach with appli...
Biologic therapy ice breaking in rheumatology, Case based approach with appli...Biologic therapy ice breaking in rheumatology, Case based approach with appli...
Biologic therapy ice breaking in rheumatology, Case based approach with appli...
 
Forensic Nursing powerpoint presentation
Forensic Nursing powerpoint presentationForensic Nursing powerpoint presentation
Forensic Nursing powerpoint presentation
 
Arthroscopic Surgery in Indore : A Minimally Invasive Guide to Joint Health
Arthroscopic Surgery in Indore : A Minimally Invasive Guide to Joint HealthArthroscopic Surgery in Indore : A Minimally Invasive Guide to Joint Health
Arthroscopic Surgery in Indore : A Minimally Invasive Guide to Joint Health
 
AI in Action: Elevating Patient Insights
AI in Action: Elevating Patient InsightsAI in Action: Elevating Patient Insights
AI in Action: Elevating Patient Insights
 
MedMatch: Your Health, Our Mission. Pitch deck.
MedMatch: Your Health, Our Mission. Pitch deck.MedMatch: Your Health, Our Mission. Pitch deck.
MedMatch: Your Health, Our Mission. Pitch deck.
 
Role of Soap based and synthetic or syndets bar
Role of  Soap based and synthetic or syndets barRole of  Soap based and synthetic or syndets bar
Role of Soap based and synthetic or syndets bar
 
GOUT UPDATE AHMED YEHIA 2024, case based approach with application of the lat...
GOUT UPDATE AHMED YEHIA 2024, case based approach with application of the lat...GOUT UPDATE AHMED YEHIA 2024, case based approach with application of the lat...
GOUT UPDATE AHMED YEHIA 2024, case based approach with application of the lat...
 
Transport across cell membrane (passive, active, vesicular)
Transport across cell membrane (passive, active, vesicular)Transport across cell membrane (passive, active, vesicular)
Transport across cell membrane (passive, active, vesicular)
 
Male Infertility Panel Discussion by Dr Sujoy Dasgupta
Male Infertility Panel Discussion by Dr Sujoy DasguptaMale Infertility Panel Discussion by Dr Sujoy Dasgupta
Male Infertility Panel Discussion by Dr Sujoy Dasgupta
 
Pharmacokinetic Models by Dr. Ram D. Bawankar.ppt
Pharmacokinetic Models by Dr. Ram D.  Bawankar.pptPharmacokinetic Models by Dr. Ram D.  Bawankar.ppt
Pharmacokinetic Models by Dr. Ram D. Bawankar.ppt
 
Cure of patients which terminally ill.pdf
Cure of patients which terminally ill.pdfCure of patients which terminally ill.pdf
Cure of patients which terminally ill.pdf
 
DNA nucleotides Blast in NCBI and Phylogeny using MEGA Xi.pptx
DNA nucleotides Blast in NCBI and Phylogeny using MEGA Xi.pptxDNA nucleotides Blast in NCBI and Phylogeny using MEGA Xi.pptx
DNA nucleotides Blast in NCBI and Phylogeny using MEGA Xi.pptx
 
PAIN/CLASSIFICATION AND MANAGEMENT OF PAIN.pdf
PAIN/CLASSIFICATION AND MANAGEMENT OF PAIN.pdfPAIN/CLASSIFICATION AND MANAGEMENT OF PAIN.pdf
PAIN/CLASSIFICATION AND MANAGEMENT OF PAIN.pdf
 
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
 
American College of physicians ACP high value care recommendations in rheumat...
American College of physicians ACP high value care recommendations in rheumat...American College of physicians ACP high value care recommendations in rheumat...
American College of physicians ACP high value care recommendations in rheumat...
 
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA .pdf
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA    .pdfSGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA    .pdf
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA .pdf
 
Generative AI in Health Care a scoping review and a persoanl experience.
Generative AI in Health Care a scoping review and a persoanl experience.Generative AI in Health Care a scoping review and a persoanl experience.
Generative AI in Health Care a scoping review and a persoanl experience.
 

Aniseikonia [ophthalmology description for medical students ]

  • 1. ANISEIKONIA  A condition wherein the images projected to the visual cortex from the two retinae are abnormally unequal in size and/or shape.  Up to 5% - well tolerated.
  • 2. Symptoms • 1. Asthenopia, i.e., eyeache, browache and tiredness • of eyes. • 2. Diplopia due to difficult binocular vision when • the difference in images of two eyes is more than • 5 percent • 3. Difficulty in depth perception.
  • 3. Etiological types Optical aniseikonia • may occur due to either inherent or acquired anisometropia of high degree. Retinal aniseikonia • may develop due to: displacement of retinal elements towards the nodal point in one eye due to stretching or oedema of the retina. Cortical aniseikonia • implies asymmetrical simultaneous perception inspite of equal size of images formed on the two retinae.
  • 4. Clinical types a) Spherical - magnified or minified equally in both meridia b) Cylindrical - magnified or minified symmetrically in one meridian . a) Prismatic - image difference increases progressively in one direction b) Pincushion - image distortion increases progressively in both directions, as seen with high plus correction in aphakia c) Barrel distortion - image distortion decreases progressively in both directions, as seen with high minus correction d) Oblique distortion- size of image is same, but oblique distortion of shape • 1. Symmetrical aniseikonia • 2. Asymetrical aniseikonia
  • 5. Treatment • 1. Optical aniseikonia may be corrected by • aniseikonic glasses, contact lenses or intraocular • lenses depending upon the situation. • 2. For retinal aniseikonia treat the cause. • 3. Cortical aniseikonia is very difficult to treat.
  • 6. APHAKIA ‘Absence of crystalline lens’ from the eye Optical point of view – condition in which lens is absent from the pupillary area Produces high degree hypermetropia
  • 8. Causes 1. Congenital absence of lens 2. Surgical aphakia 3. Aphakia due to absorption of lens matter 4. Trauma extrusion of lens 5. Posterior dislocation of lens
  • 9. Optical changes in the eye after removal of crystalline lens • High degree hypermetropia • Total power of eye is reduced from +60D to about +44D • Anterior focal point becomes 23.2 mm in front of the cornea ( N : 15.7 mm ) • Posterior focal point is about 7mm behind the eyeball i.e 31mm behind the cornea • Accommodation is lost completely
  • 10. Clinical features SYMPTOMS – • Defective vision : for both far and near • Erythropsia and cyanopsia SIGNS – • Limbal scar • Anterior chamber deeper than normal • Iridodonesis • Pupil is jet black in colour • Purkinje image test shows only two images • Fundus examination shows hypermetrophic small disc • Retinoscopy and autorefractometry reveals high hypermetropia
  • 11. Treatment  Spectacles –  +10D with cylindrical lenses for surgically induced astigmatism in previously emmetropic patients  An addition of +3 to +4 D is required for near vision to compensate for loss of accommodation.  Contact lens  IOL Implantation o Primary IOL implantation- during cataract surgery o Secondary IOL implantation- already aphakic patients  Refractive corneal surgery o Keratophakia, Epikeratophakia, Hyperopic LASIK
  • 12.  Keratophakia. In this procedure a lenticule prepared from the donor cornea is placed between the lamellae of patient's cornea.  Epikeratophakia. In this procedure, the lenticule prepared from the donor cornea is stitched over the surface of cornea after removing the epithelium.  Hyperopic Lasik
  • 13. Anisometropia Condition where total refraction of two eyes is unequal
  • 14. degree of anisometropia difference in size of two retinal images 1 D 2 % No concern 2.5 D 5 % Well tolerated 2.5 D to 4 D can be tolerated depending upon the individual sensitivity > 4 D not tolerated Matter of concern
  • 15. ETIOLOGY – 1.Congenital and developmental anisometropia - due to differential growth of eyeballs 2.Acquired anisometropia - asymmetric age change - removal of cataractous lens - implantation of IOL of wrong power
  • 16. CLINICAL TYPES – 1.Simple anisometropia - Simple myopic anisometropia - Simple hypermetropic anisometropia 2. Compound anisometropia - Compound myopic anisometropia - Compound hypermetropic anisometropia 3.Mixed anisometropia / antimetropia 4.Simple astigmatic anisometropia 5.Compound astigmatic anisometropia
  • 17. STATUS OF VISION IN ANISOMETROPIA – 1.Small degree anisometropia – Binocular vision 2.When refractive error in one eye is of high degree – Uniocular vision 3.When one eye is hypermetropic and the other is myopic – Alternate vision DIAGNOSIS – • Retinoscopic examination • Autorefractometry
  • 18. TREATMENT – 1.Spectacles 2.Contact lenses 3.IOL implantation 4.Refractive corneal surgery 5.Phakic refractive lenses ( PRL ) 6.Refractive lens exchange ( RLE )
  • 20. Astigmatism • Type of refractive error wherein the refraction varies in the different meridian. • Consequently, the rays of light entering in the eye cannot converge to a point focus but form focal lines
  • 21. Regular BASED ON ETIOLOGY 1. Corneal astigmatism 2. Lenticular astigmatism i. Curvatural Eg.lenticonus ii. Positional Eg. subluxation. iii. Index. 3. Retinal astigmatism Depending upon the axis and the angle between the two principal meridia 1. With-the-rule astigmatism 2. Against-the-rule astigmatism 3. Oblique astigmatism 4. Bioblique astigmatism Depending upon the position of the two focal lines in relation to retina Simple astigmatism, Compound astigmatism Mixed astigmatism
  • 22. • Symptoms Defective vision; blurring of objects; (iii) depending upon the type and degree of astigmatism, objects may appear proportionately elongated; and (iv) asthenopic symptoms, which are marked especially in small amount of astigmatism, consist of a dull ache in the eyes, headache, early tiredness of eyes and sometimes nausea and even drowsiness. • Signs • 1. Different power in two meridia is revealed on • retinoscopy or autorefractometry. • 2. Oval or tilted optic disc may be seen on • ophthalmoscopy in patients with high degree of • astigmatism. • 3. Head tilt. The astigmatic patients may (very • exceptionally) develop a torticollis in an attempt • to bring their axes nearer to the horizontal or • vertical meridians. • 4. Half closure of the lid. Like myopes, the astigmatic • patients may half shut the eyes to achieve the • greater clarity of stenopaeic vision.
  • 23. Treatment • 1. Optical treatment • i. Spectacles with full correction of cylindrical power and appropriate axis should be used for distance and near vision. • ii. Contact lenses. Rigid contact lenses may correct upto 2-3 of regular astigmatism, while soft contact lenses can correct only little astigmatism. For higher degrees of astigmatism toric contact lenses are needed. In order to maintain the correct axis of toric lenses, ballasting or truncation is required. • 2. Surgical correction
  • 24. IRREGULAR ASTIGMATISM • It is characterized by an irregular change of refractive power in different meridia. There are multiple meridian which admit no geometrical analysis. • Etiological types • 1. Curvatural irregular astigmatism is found in patients with extensive corneal scars or keratoconus. • 2. Index irregular astigmatism due to variable refractive index in different parts of the crystalline lens may occur rarely during maturation of cataract. • Symptoms of irregular astigmatism include: • _ Defective vision, • _ Distortion of objects and • _ Polyopia.
  • 25. • Investigations • 1. Placido's disc test reveales distorted circles • 2. Photokerotoscopy and computerized corneal topography give photographic record of irregular corneal curvature. • Treatment 1. Optical treatment - contact lens 2. Phototherapeutic keratectomy (PTK) 3. Surgical treatment is indicated in extensivecorneal and consists of penetrating keratoplasty.
  • 26. Refractive surgery for astigmatism • Refractive surgical techniques employed for myopia can be adapted to correct astigmatism alone or simultaneously with myopia as follows: • 1. Astigmatic keratotomy (AK) refers to makingtransverse cuts in the mid periphery of the steep corneal meridian • 2. Photo-astigmatic refractive keratotomy (PARK) • 3. LASIK to correctastigmatism upto 5D. • Management of post-keratoplasty astigmatism • 1. Selective removal of sutures in steep meridians