أسئلة المحاضرة التاسعة رمد (قبل التعديل)

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Questions and Answers

What are the characteristic visual disturbances associated with incipient cataract?

Incipient cataract leads to difficulties in night vision, mono-ocular diplopia, and haloes around light.

How does immature cataract differ from mature cataract in terms of visual acuity?

Immature cataract has visual acuity of counting fingers or better, while mature cataract usually presents as hand motion or worse.

What common feature is absent in mature cataracts that is present in immature cataracts?

In mature cataracts, the iris shadow is absent, whereas it is present in immature cataracts.

Describe the changes in color and opacity between immature and mature cataracts.

Immature cataracts appear grey and are not completely opaque, while mature cataracts are totally opaque and appear white. Signup and view all the answers

What are the indications for cataract surgery?

Cataract surgery is indicated to improve vision, treat underlying complications, and address any retinal disease. Signup and view all the answers

What is the approximate dioptric power of the eye?

16-18 D inside the eye and 70 D outside the eye. Signup and view all the answers

List two congenital causes of visual impairment.

Connective tissue diseases and congenital glaucoma. Signup and view all the answers

What is one symptom associated with lenticular myopia?

Changing astigmatism. Signup and view all the answers

What is monocular diplopia and one possible sign of it?

Monocular diplopia is double vision in one eye; a possible sign is a deep anterior chamber. Signup and view all the answers

What is the primary optical correction method for visual impairments?

Glasses or contact lenses. Signup and view all the answers

What type of cataract is characterized by yellowing due to nuclear sclerosis?

Nuclear cataract. Signup and view all the answers

Which type of cataract affects near vision more than far vision and is often seen in bright conditions?

Posterior subcapsular cataract. Signup and view all the answers

What is a common characteristic of cortical cataracts?

They begin with precataractous changes. Signup and view all the answers

What are the advantages of using ECCE over ICCE in cataract surgery?

ECCE has less vitreous loss, the capsule acts as a barrier between aqueous and vitreous, serves as a bag for IOL, and reduces the risk of retinal detachment and macular edema. Signup and view all the answers

How does phacoemulsification benefit postoperative recovery in cataract surgery?

Phacoemulsification allows for earlier rehabilitation and results in less induced astigmatism. Signup and view all the answers

What are some common complications of cataract surgery during the postoperative period?

Common complications include posterior capsule opacification, endophthalmitis, corneal edema, astigmatism, iris prolapse, IOL decentration, retinal detachment, and cystoid macular edema. Signup and view all the answers

In the context of ocular surgery, what is the role of A-Scan ultrasound and keratometry?

A-Scan ultrasound and keratometry are used for IOL power calculation to determine the appropriate lens strength for each patient. Signup and view all the answers

What local anesthesia options are available for patients undergoing cataract surgery?

Local anesthesia options include topical anesthetics and regional blocks, while general anesthesia can also be considered. Signup and view all the answers

What is the primary role of the crystalline lens in the eye?

The crystalline lens primarily focuses light onto the retina, contributing about one-third of the eye's refractive power. Signup and view all the answers

Describe the anatomical position of the crystalline lens in relation to the iris.

The crystalline lens lies in the pupillary area behind the iris, separating the eyeball into anterior and posterior segments. Signup and view all the answers

What are the different nuclei of the lens, and how are they formed?

The lens has three nuclei: the embryonic nucleus, foetal/infantile nucleus, and adult nucleus, formed during the lens's development from the surface ectoderm. Signup and view all the answers

How are the anterior and posterior capsules of the lens different in structure?

The anterior capsule is thicker than the posterior capsule and is lined by anterior subcapsular epithelium, while the posterior capsule is not lined by epithelium. Signup and view all the answers

Explain the significance of the lens sutures.

Lens sutures are the junctions where lens fibers meet, with the sutures in front of the nucleus taking an erect (Y) shape and those behind it being inverted (Y) shaped. Signup and view all the answers

What role does the ciliary body play in relation to the crystalline lens?

The ciliary body attaches the crystalline lens to the eye via suspensory ligaments or zonules, allowing for accommodation during focusing. Signup and view all the answers

Discuss the refractive index difference between the lens cortex and nucleus.

The refractive index of the lens cortex is 1.38, while the nucleus has a higher refractive index of 1.42. Signup and view all the answers

What embryological structures lead to the formation of the crystalline lens?

The crystalline lens develops from the surface ectoderm, which forms a lens placode that eventually separates to create a lens vesicle. Signup and view all the answers

What clinical manifestations might indicate the presence of incipient cataract?

Night vision impairment, mono-ocular diplopia, and haloes around light are common. Signup and view all the answers

How would you differentiate between immature and mature cataracts based on iris shadow?

Iris shadow is present in immature cataracts but absent in mature cataracts. Signup and view all the answers

In what way does color change between immature and mature cataracts aid in diagnosis?

Immature cataracts typically appear grey, while mature cataracts appear white. Signup and view all the answers

What are the potential complications that may arise from a hypermature cataract?

Hypermature cataracts may lead to lens-induced glaucoma and uveitis. Signup and view all the answers

What is the significance of identifying symptoms like polyopia in assessing cataract progression?

Polyopia can indicate increasing cataract severity, affecting the patient's visual quality. Signup and view all the answers

What are the primary advantages of performing ECCE compared to ICCE during cataract surgery?

ECCE offers less vitreous loss, serves as a barrier to retinal detachment, and provides a bag for IOL placement. Signup and view all the answers

Explain the role of the posterior capsule during cataract surgery.

The posterior capsule acts as a barrier between aqueous and vitreous humor, which helps reduce the risk of retinal detachment. Signup and view all the answers

Identify and describe two intraoperative complications that can arise during cataract surgery.

Vitreous loss can occur when the vitreous gel prolapses, and expulsive hemorrhage may happen due to rapid bleeding from the ciliary body. Signup and view all the answers

What is phacoemulsification, and how does it improve postoperative recovery for cataract patients?

Phacoemulsification is a technique using ultrasound to break up the cataract, which leads to earlier rehabilitation and reduced induced astigmatism. Signup and view all the answers

List two common postoperative complications associated with cataract surgery and their implications.

Posterior capsule opacification (PCO) can lead to vision deterioration, while endophthalmitis poses a risk of severe infection. Signup and view all the answers

What dioptric power does the eye achieve inside the eye?

16-18 D. Signup and view all the answers

Identify one cause of visual impairment related to congenital factors.

Connective tissue diseases. Signup and view all the answers

Name one method for the optical correction of visual impairments.

Glasses or contact lenses. Signup and view all the answers

What type of cataract is characterized by an increase in refractive index of the lens nucleus?

Nuclear cataract. Signup and view all the answers

How does posterior subcapsular cataract primarily affect vision?

It affects near vision more than far vision. Signup and view all the answers

What is a common visual effect of nuclear cataract on presbyopes?

They can see without reading glasses. Signup and view all the answers

Which type of traumatic injury can lead to a specific form of cataract known as 'glass blowers cataract'?

Ultraviolet radiation injury. Signup and view all the answers

What possibly indicates the presence of a large globe in relation to congenital glaucoma?

Myopia. Signup and view all the answers

What anatomical feature divides the eyeball into anterior and posterior segments?

The crystalline lens divides the eyeball into anterior and posterior segments. Signup and view all the answers

What is the significance of the lens sutures in the crystalline lens?

Lens sutures allow lens fibers to meet and are important for lens integrity. Signup and view all the answers

Describe the difference in thickness between the anterior and posterior capsules of the crystalline lens.

The anterior capsule is thicker than the posterior capsule. Signup and view all the answers

Why does the posterior pole of the lens represent its thinnest area?

The posterior pole is thinnest due to the lens’s structural adaptation for focusing light. Signup and view all the answers

What type of cells contribute to the formation of new cortical fibers throughout life in the lens?

Anterior subcapsular epithelial cells proliferate to form new cortical fibers. Signup and view all the answers

What embryological structure leads to the formation of the lens vesicle?

The lens placode, derived from surface ectoderm, forms the lens vesicle during embryonic development. Signup and view all the answers

What are the three nuclei of the crystalline lens, and when is each formed?

The three nuclei are the embryonic nucleus, foetal/infantile nucleus, and adult nucleus. Signup and view all the answers

How does the refractive index differ between the lens cortex and nucleus?

The cortex has a refractive index of 1.38, while the nucleus has a higher index of 1.42. Signup and view all the answers

What visual defect is predominantly associated with incipient cataract?

Increased glare from lights Signup and view all the answers

Which characteristic differentiates immature cataract from mature cataract?

Color change from grey to white Signup and view all the answers

Which of the following describes the visual acuity of a mature cataract?

Hand motion perception only Signup and view all the answers

What symptom commonly indicates the progression to a hypermature cataract?

Lens discoloration Signup and view all the answers

Which of the following conditions may result from advanced cataract stages?

Intraocular pressure increase Signup and view all the answers

Which statement accurately describes the advantages of ECCE over ICCE in cataract surgery?

ECCE provides better support for intraocular lens placement than ICCE. Signup and view all the answers

What is the primary benefit of performing phacoemulsification during cataract surgery?

It facilitates quicker rehabilitation and reduces astigmatism. Signup and view all the answers

Which of the following is a complication associated with cataract surgery during the intraoperative period?

Iris prolapse Signup and view all the answers

Which two methods are combined to determine IOL power calculation?

A-Scan ultrasound and Keratometry Signup and view all the answers

Which complication is often encountered postoperatively in cataract surgery patients?

Posterior capsule opacification Signup and view all the answers

What is the approximate dioptric power of the eye outside the eye?

70 D Signup and view all the answers

Which factor is NOT associated with acquired visual impairment?

Congenital disorders Signup and view all the answers

Which of the following types of cataract affects vision primarily in bright lighting conditions?

Posterior subcapsular cataract Signup and view all the answers

What is a common consequence of nuclear sclerosis in nuclear cataract?

Decreased far vision Signup and view all the answers

Which of the following does NOT describe a symptom of lenticular myopia?

Severe photophobia Signup and view all the answers

In which condition might an individual experience color changes in their vision due to cataract?

Nuclear cataract Signup and view all the answers

Which of the following types of cataract is commonly associated with aging?

Senile cataract Signup and view all the answers

What is the effect of electric injury on the lens?

Coagulation of lens proteins Signup and view all the answers

What is the main structural difference between the anterior and posterior capsules of the crystalline lens?

The anterior capsule contains epithelium while the posterior capsule does not. Signup and view all the answers

Which statement accurately describes the lens and its components?

Lens fibers converge at sutures in a Y-shaped configuration. Signup and view all the answers

What is the primary role of the ciliary processes in relation to the crystalline lens?

They hold the lens in place via suspensory ligaments. Signup and view all the answers

What is the significance of the lens sutures in the crystalline lens?

They provide structural integrity by holding lens fibers together. Signup and view all the answers

What embryological component ultimately leads to the formation of the adult lens?

Lens placode. Signup and view all the answers

Which characteristic of the lens indicates it is the thinnest at the posterior pole?

It is less curved compared to the anterior surface. Signup and view all the answers

What does the continuous proliferation of the anterior subcapsular epithelium contribute to?

Creation of new cortical fibers. Signup and view all the answers

Which of the following statements about the refractive power of the lens is true?

It contributes significantly to the overall refractive power of the eye. Signup and view all the answers

What visual symptom is most commonly associated with incipient cataract?

Affected night vision Signup and view all the answers

In which type of cataract is the iris shadow absent?

Mature cataract Signup and view all the answers

What color change is typically observed in mature cataracts?

White Signup and view all the answers

What is a primary advantage of using ECCE over ICCE in cataract surgery?

Less vitreous loss Signup and view all the answers

What is one of the common complications associated with hypermature cataracts?

Increased eye pressure Signup and view all the answers

Which complication is most commonly associated with postoperative cataract surgery?

Endophthalmitis Signup and view all the answers

What visual acuity is associated with immature cataract?

Counting fingers or better Signup and view all the answers

During cataract surgery, the use of phacoemulsification primarily leads to what outcome?

Earlier rehabilitation Signup and view all the answers

What is the purpose of performing IOL power calculation before surgery?

To determine the appropriate intraocular lens strength Signup and view all the answers

What distinguishes phacoemulsification from conventional cataract surgery techniques?

It employs ultrasound energy Signup and view all the answers

What is the effect of posterior subcapsular cataract on vision?

Substantially affects near vision, especially in bright lighting. Signup and view all the answers

Which of the following is NOT an acquired cause of visual impairment?

Anemia Signup and view all the answers

What dioptric power is typically observed outside the eye?

70 D Signup and view all the answers

Which signs might indicate the presence of monocular diplopia?

Deep anterior chamber and tremulous iris Signup and view all the answers

Which type of cataract is specifically known to become brown or black at late stages?

Nuclear cataract Signup and view all the answers

What is the primary method used for optical correction of visual impairments?

Use of corrective lenses Signup and view all the answers

What is a common refractive error associated with lenticular myopia?

Increased nearsightedness due to lenticular changes. Signup and view all the answers

Which traumatic injury is specifically related to 'glass blowers cataract'?

Injury due to extreme heat or flame. Signup and view all the answers

What is the primary function of the crystalline lens in the eye?

To refract light to focus images on the retina Signup and view all the answers

Which feature differentiates the anterior and posterior capsules of the lens?

The anterior capsule is lined by a subcapsular epithelium Signup and view all the answers

What is the structure that forms the thinnest area of the lens?

Posterior pole Signup and view all the answers

Which statement regarding lens fibers is correct?

They meet at the lens sutures forming distinct shapes Signup and view all the answers

What embryological origin does the lens arise from?

Surface ectoderm Signup and view all the answers

How does the refractive index of the lens nucleus compare to the cortex?

The nucleus has a higher refractive index than the cortex Signup and view all the answers

What is the role of suspensory ligaments in relation to the crystalline lens?

They attach the lens to the ciliary body Signup and view all the answers

What structural feature is found at the center of both the anterior and posterior capsules of the lens?

Lens poles Signup and view all the answers

Study Notes

Anatomy

The crystalline lens is a clear, biconvex structure located behind the iris.
It divides the eyeball into anterior and posterior segments.
Connected to the ciliary processes by suspensory ligaments.
Covered by an anterior and posterior capsule, joining at the equator.
Anterior capsule is thicker, lined by anterior subcapsular epithelium.
Posterior capsule is not lined by epithelium.
The center of the anterior capsule is the anterior pole, and the posterior capsule is the posterior pole.
The line connecting these poles is the lens axis.
The lens cortex is formed from anterior subcapsular epithelium, and represents soft fibers inner to the anterior and posterior capsules.
The epithelium continually forms new cortical fibers throughout life.
Lens fibers form sutures; anterior sutures have an erect (Y) shape, posterior sutures have an inverted (Y) shape.
The lens has three nuclei: embryonic, foetal/infantile, adult.

Embryology

Develops embryologically from the surface ectoderm, forming a lens placode.
Then separates to form a lens vesicle.
The lens nucleus at birth is the embryonic nucleus.
This is partly formed by migration of the posterior subcapsular epithelium.
The lens lacks blood vessels and nerve endings.
Initially vascularized during early embryonic life by the posterior hyaloid artery.
With development, the posterior hyaloid artery obliterates, forming the tunica vasculosa lentis.

Function

Refraction: accounts for about one-third of the eye's refractive power.
Dimensions of an adult lens: approximately 10mm diameter and 4mm thick.
Radius of curvature: anterior surface (10mm), posterior surface (6mm).
Refractive index: cortex (1.38), nucleus (1.42).
Dioptric power: inside the eye (16-18 Diopters), outside the eye (70 Diopters).
Accommodation: allows the eye to focus on near objects.
Protection: protects the retina from harmful ultraviolet (UV) rays.

Lens Displacement

Etiology: Congenital (connective tissue diseases) or acquired (trauma, hypermature cataract, anterior uveal tumor, large globe).
Symptoms: Visual impairment (lenticular myopia, changing astigmatism, prismatic effect, monocular diplopia).
Signs: Deep anterior chamber, tremulous iris, possible visualization of lens edge or zonules.
Management: Optical correction (glasses or contact lenses), surgical removal.

Aphakia

Definition: Absence of the lens from the pupillary area.
Etiology: Congenital, surgical, loss through perforated corneal ulcer, or posterior dislocation.
Symptoms: Strong hypermetropia (increase in refractive error).
Loss of accomodation: ability to focus on near objects is lost.
Optical conditions: Increase in image size.
Clinical picture: Decreased visual acuity, deep anterior chamber, tremulous iris, jet black pupil, absence of Purkinje images.

Management (glasses, contact lenses, IOL implantation)

Glasses: For bilateral cases (thick, heavy, decrease field of vision, increase image size).
Contact lenses: Unilateral or bilateral (used with care, increase size of image).
IOL implantation: Primary or secondary; posterior chamber, anterior chamber, scleral fixation.
Investigations for power determination: A-scan US, IOL Master.

Cataract

Definition: Opacification of the lens.
Classification: Congenital and Developmental (Lamellar, Polar, Blue Dot, Coronary) or Acquired (Senile, Traumatic, Complicated, Toxic).
Causes: Congenital/Developmental (trauma, metabolic disorders, ocular anomalies, infections, drugs, irradiation, nutritional).
Causes: Acquired (senile, traumatic, complicated, toxic).
Clinical presentations: Leucocoria, squint/amblyopia, nystagmus, and diminution of vision (mild, moderate or severe).
Types: Nuclear, Posterior Subcapsular, Cortical (precataractous changes, incipient, immature, mature, hypermature).

Acquired Cataract

Causes: Toxins or drugs (steroid induced).
Types: Toxic (secondary to ocular or systemic disease), Complicated (weakness of accommodation, change/change in refractive index).

Traumatic Cataract

Blunt trauma: Rosette-shaped cataract, Vossious ring, lens displacement.
Penetrating trauma: Direct impact, Lenticulo-corneal touch, trauma to lens capsule, chemical injuries (alkalis > acids), radiation injury (ultraviolet, microwave, ionizing, infrared), electric injury (coagulation of lens proteins, IOFB-iron/copper lead to sidrosis, chalcosis, sunflower's cataract).

IOL Calculation

Using A-scan US + Keratometry
Types of Anesthesia: Local, General
Types of Procedures: ICCE, ECCE

Intraoperative and Postoperative Complications

Intraoperative: Vitreous loss, Expulsive hemorrhage.
Postoperative: Posterior capsule opacification (PCO), Endophthalmitis, Corneal edema, Astigmatism, Iris prolapse, IOL decentration, RD, CME.

Phacoemulsification

A surgical technique.

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