أسئلة المحاضرة الـ 11 رمد (قبل التعديل)

RGP contact lenses act as a second surface for the eye, compensating for corneal irregularities and serving as the new reflective surface.

Keratoplasty is significant when there is a difference of greater than 1D in refraction between the two eyes, leading to issues like headaches and eye strain.

Contact lenses reduce the difference in retinal image size to about 6%, thus mitigating visual discomfort caused by anisometropia.

<p>Accommodative asthenopia is characterized by headaches, eye ache, burning sensations, and difficulty in near vision.</p> Signup and view all the answers

<p>Muscular asthenopia is mainly caused by heterophoria or latent squint, leading to difficulty maintaining steady vision.</p> Signup and view all the answers

<p>Presbyopia results from sclerosed crystalline lens fibers and a weaker ciliary muscle, making near vision increasingly difficult.</p> Signup and view all the answers

<p>Glasses for accommodating asthenopia typically involve adding plus lenses to the existing distance correction.</p> Signup and view all the answers

<p>LASIK and intraocular lenses create a difference of less than 1% in image size, making them the most convenient option for correcting refractive errors.</p> Signup and view all the answers

<p>Axial myopia involves an increase in the axial length affecting the posterior pole, while curvature myopia is related to abnormalities in the lens or corneal shape.</p> Signup and view all the answers

<p>Indistinct far vision and defective night vision are two common symptoms of myopia.</p> Signup and view all the answers

<p>A temporal crescent at the optic disc and posterior staphyloma, where the sclera bulges out, may be observed.</p> Signup and view all the answers

<p>Rhegmatogenous retinal detachment can occur due to a tear in the retina allowing fluid to seep in and detach the retina from its bed.</p> Signup and view all the answers

<p>Foster Fuch's spots are dark pigmented circular areas found in cases of chorioretinal degeneration associated with myopia.</p> Signup and view all the answers

<p>Vitreous degeneration can lead to opacities, detachment, and even retinal tears or hemorrhages.</p> Signup and view all the answers

<p>Degenerative myopia typically begins at 5-10 years of age and continues to progress until around 20 years.</p> Signup and view all the answers

<p>In axial myopia, the anterior segment typically remains normal, whereas the posterior segment is affected by increased axial length.</p> Signup and view all the answers

<p>Phakic IOL implantation and clear lens extraction with or without IOL implantation.</p> Signup and view all the answers

<p>RK involves creating multiple linear incisions in the anterior cornea to flatten it, thereby reducing its focusing power and decreasing myopia.</p> Signup and view all the answers

<p>Refractive keratotomy and astigmatic keratotomy.</p> Signup and view all the answers

<p>The main advantage is that RK spares a 3 mm optical center, reducing the risk of complications in that vital area.</p> Signup and view all the answers

<p>Femtolasers are used to perform bladeless RK incisions.</p> Signup and view all the answers

<p>Young adults with stable myopia ranging from -1 to -6 D and minimal astigmatic error.</p> Signup and view all the answers

<p>Corneal rings and inlays aim to correct refractive errors by altering the shape of the cornea without the need for incisions.</p> Signup and view all the answers

<p>Radial keratotomy is almost one-fourth the cost of laser refractive surgery.</p> Signup and view all the answers

<p>The primary indication for performing PRK surgery is the management of post-keratoplasty induced astigmatism.</p> Signup and view all the answers

<p>PRK involves removing only 80 microns of corneal tissue, whereas LASIK typically removes about 120 microns to create a flap.</p> Signup and view all the answers

<p>Disadvantages of PRK include severe postoperative pain, the risk of residual corneal haze, and the possibility of destructive corneal infections due to epithelium removal.</p> Signup and view all the answers

<p>The estimated accuracy rate of PRK in achieving desired corrections is around 95%, with a +/- 0.5D correction.</p> Signup and view all the answers

<p>LASIK avoids complications related to flap formation and suction cup use, which can pressurize the globe and cause retinal issues.</p> Signup and view all the answers

<p>PRK uses a computer-controlled, high accuracy excimer laser to reshape the cornea, correcting myopia, hypermetropia, and astigmatism.</p> Signup and view all the answers

<p>The maximum range of visual correction achievable with LASIK is from -8 to +5 diopters.</p> Signup and view all the answers

<p>Mitomycin-C is significant in PRK because it decreases the incidence and density of post-operative corneal haze.</p> Signup and view all the answers

<p>The typical flap thickness is between 100 to 120 microns.</p> Signup and view all the answers

<p>An advantage of LASIK is rapid visual results, while a disadvantage is the requirement of greater surgical skill.</p> Signup and view all the answers

<p>Flap wrinkling (striae) can occur if the flap is too thin.</p> Signup and view all the answers

<p>ICRS reshape the anterior corneal surface by removing material from the center or adding it to the periphery.</p> Signup and view all the answers

<p>The use of ICRS for myopia has faded due to limited correction range and induced astigmatism.</p> Signup and view all the answers

<p>CK is a noninvasive procedure using radio frequency, which causes peripheral shrinkage and central steepening of the cornea.</p> Signup and view all the answers

<p>Risks include free flap, incomplete flap, or flap buttonhole complications.</p> Signup and view all the answers

<p>Femtosecond lasers eliminate pain and corneal haze that are often seen in RK and PRK surgeries.</p> Signup and view all the answers

<p>FS laser provides greater surgeon control and reduced incidence of flap complications such as buttonholes and free caps.</p> Signup and view all the answers

<p>ReLex uses femto-laser to create a corneal pocket with a stromal lenticule, which is retrieved through a small incision.</p> Signup and view all the answers

<p>A notable disadvantage is the higher cost compared to traditional LASIK techniques.</p> Signup and view all the answers

<p>OBL can interfere with the excimer laser eye tracker, affecting tracking and registration accuracy.</p> Signup and view all the answers

<p>Lamellar keratitis occurs in the flap interface with inflammation primarily in the anterior stroma, unlike DLK which has different inflammatory patterns.</p> Signup and view all the answers

<p>Postoperative outcomes include less postoperative dry eye and less corneal denervation.</p> Signup and view all the answers

<p>The small incision reduces biomechanical instability and the risk of corneal ectasia.</p> Signup and view all the answers

<p>One main drawback is the difficulty in lifting the flap if retreatment becomes necessary.</p> Signup and view all the answers

<p>Cosmetic contact lenses may pose an economic burden for poor patients and can require ongoing purchases of cleaning solutions.</p> Signup and view all the answers

<p>Infection, such as acanthamoeba keratitis, can occur due to poor hygiene or contamination of contact lenses.</p> Signup and view all the answers

<p>Allergic (giant papillary) or infective conjunctivitis may occur occasionally in contact lens wearers.</p> Signup and view all the answers

<p>Surgical correction is indicated in cases of optical intolerance to contact lenses, mechanical difficulties in fitting glasses, or cosmetic concerns.</p> Signup and view all the answers

<p>Corneal epithelial edema and vascularization may occur due to hypoxia associated with contact lens wear.</p> Signup and view all the answers

<p>Tear film, cornea, and crystalline lens.</p> Signup and view all the answers

<p>This condition refers to ametropia, specifically types like myopia or hypermetropia.</p> Signup and view all the answers

<p>The fovea centralis is the point on the retina where light rays are focused for sharp vision.</p> Signup and view all the answers

<p>+58 to +60 diopters.</p> Signup and view all the answers

<p>Axial ametropia refers to an abnormal length of the eyeball affecting focus, leading to myopia or hypermetropia.</p> Signup and view all the answers

<p>The nodal point is the optical center of refraction located just behind the lens.</p> Signup and view all the answers

<p>Cycloplegia is induced to temporarily paralyze the ciliary muscle for accurate measurement of refraction.</p> Signup and view all the answers

<p>Abnormal curvature can lead to curvature ametropia, resulting in distorted vision.</p> Signup and view all the answers

<p>The posterior pole is affected by an increase in axial length, leading to visual distortions.</p> Signup and view all the answers

<p>In index myopia, the refractive index of the lens nucleus increases, affecting the overall refractive power.</p> Signup and view all the answers

<p>Curvature myopia may lead to keratoconus or corneal ectasia, impacting visual clarity.</p> Signup and view all the answers

<p>Signs such as the temporal crescent and posterior staphyloma indicate retinal changes and increased risk of detachment.</p> Signup and view all the answers

<p>Progressive myopia often includes indistinct far vision and defective night vision.</p> Signup and view all the answers

<p>Vitreous degeneration can lead to retinal tears and detachment, increasing the risk of visual impairment.</p> Signup and view all the answers

<p>Degenerative myopia typically begins at birth and remains stationary after the age of 20.</p> Signup and view all the answers

<p>Retinal detachment and chorioretinal degeneration are significant complications of high myopia.</p> Signup and view all the answers

<p>Advantages include durability and firmness, while disadvantages are corneal hypoxia leading to corneal oedema and possible foreign body sensation.</p> Signup and view all the answers

<p>They are beneficial for corneal ulcers, chemical burns, and wound healing processes like descemetocele.</p> Signup and view all the answers

<p>They allow for corrected vision at multiple distances, reducing the need for additional glasses post-surgery.</p> Signup and view all the answers

<p>Gas permeable lenses minimize corneal hypoxia, providing better oxygen flow to the cornea compared to soft lenses.</p> Signup and view all the answers

<p>They provide a regular corneal surface and mechanical support, improving vision quality in affected patients.</p> Signup and view all the answers

<p>Soft contact lenses are hydrophilic, making them comfortable and stable due to their ability to conform to the eye's shape.</p> Signup and view all the answers

<p>They decrease the likelihood of serious injuries and provide better optics with a wider field of vision.</p> Signup and view all the answers

<p>They consist of HEMA or related hydrophilic polymers, allowing them to absorb moisture and conform well to the eye.</p> Signup and view all the answers

<p>RK flattens the corneal curvature by making multiple radial incisions, decreasing myopia.</p> Signup and view all the answers

<p>Radial keratotomy is contraindicated in patients with high astigmatism or unstable myopia.</p> Signup and view all the answers

<p>Astigmatic keratotomy relies on asymmetrical incisional surgery to flatten the steeper meridian of the cornea.</p> Signup and view all the answers

<p>The central optical zone is preserved to maintain critical vision quality while reducing myopia.</p> Signup and view all the answers

<p>Radial keratotomy is approximately one-fourth the cost of laser refractive surgeries.</p> Signup and view all the answers

<p>Radial keratotomy incisions are now often created using femto-laser technology, making them bladeless.</p> Signup and view all the answers

<p>The depth of RK incisions varies according to the severity of myopia, potentially reaching just above Descemet’s membrane.</p> Signup and view all the answers

<p>One potential complication is peripheral scarring, which may affect night vision or overall visual quality.</p> Signup and view all the answers

<p>Induced astigmatism is a common complication that may require additional treatment.</p> Signup and view all the answers

<p>A zero power posterior chamber IOL is used to slow the incidence of posterior capsular opacification and to reinforce the posterior capsule.</p> Signup and view all the answers

<p>One disadvantage is that post-operative refraction may not be precise, leading to a diopter of over or under correction.</p> Signup and view all the answers

<p>A small corneal incision is made through which the phakic lens is implanted just in front of or behind the iris.</p> Signup and view all the answers

<p>Preexisting systemic diseases such as diabetes or autoimmune diseases are contraindications for phakic IOL implantation.</p> Signup and view all the answers

<p>Patients experience a loss of natural accommodative power, which affects their ability to focus on near objects.</p> Signup and view all the answers

<p>The required anterior chamber depth for phakic IOL implantation is 3.00 mm or greater.</p> Signup and view all the answers

<p>Like cataract surgery, the complications such as endophthalmitis can occur after phakic lens implantation.</p> Signup and view all the answers

<p>Corneal epithelial edema</p> Signup and view all the answers

<p>Increased field of vision</p> Signup and view all the answers

<p>Anisometropia with intolerance to contact lenses</p> Signup and view all the answers

<p>Usage for aesthetic enhancement, such as colored lenses</p> Signup and view all the answers

<p>Nose or orbit configurations difficult for spectacles</p> Signup and view all the answers

<p>Normal optical condition</p> Signup and view all the answers

<p>Retina</p> Signup and view all the answers

<p>Axial ametropia</p> Signup and view all the answers

<p>To create a red reflex in the eye</p> Signup and view all the answers

<p>Myopia</p> Signup and view all the answers

<p>It causes myopia</p> Signup and view all the answers

<p>+58 to +60D</p> Signup and view all the answers

<p>Cornea</p> Signup and view all the answers

<p>Axial myopia</p> Signup and view all the answers

<p>Around 10D</p> Signup and view all the answers

<p>Apparent convergent squint</p> Signup and view all the answers

<p>Temporal crescent</p> Signup and view all the answers

<p>Index myopia</p> Signup and view all the answers

<p>Cataract formation</p> Signup and view all the answers

<p>It progresses significantly during the teenage years.</p> Signup and view all the answers

<p>Bulging of the sclera at the posterior pole</p> Signup and view all the answers

<p>Corneal steepening from excessive stromal tissue</p> Signup and view all the answers

<p>Their effectiveness relies on the thickness and diameter of the device</p> Signup and view all the answers

<p>High risk of inducing astigmatism</p> Signup and view all the answers

<p>Inability to achieve a precise flap thickness</p> Signup and view all the answers

<p>Removal of material from the periphery flattens the center</p> Signup and view all the answers

<p>They provide faster healing due to less corneal disruption</p> Signup and view all the answers

<p>Increased risk of diffuse lamellar keratitis</p> Signup and view all the answers

<p>Higher cost compared to other methods</p> Signup and view all the answers

<p>It helps reduce the incidence of posterior capsular opacification (PCO).</p> Signup and view all the answers

<p>A corneal endothelial cell count below the acceptable threshold.</p> Signup and view all the answers

<p>Retinal detachment (RD)</p> Signup and view all the answers

<p>Induced astigmatism</p> Signup and view all the answers

<p>Corneal epithelium</p> Signup and view all the answers

<p>Active anterior segment disease</p> Signup and view all the answers

<p>Difficulty focusing on near objects</p> Signup and view all the answers

<p>Diabetes Mellitus (DM)</p> Signup and view all the answers

<p>Reduced incidence of flap complications</p> Signup and view all the answers

<p>Flap thickness and diameter control</p> Signup and view all the answers

<p>Located in the flap anterior stroma</p> Signup and view all the answers

<p>2-4 mm</p> Signup and view all the answers

<p>Interference with eye tracker registration</p> Signup and view all the answers

<p>Flap-related complications</p> Signup and view all the answers

<p>Patient comfort during the procedure</p> Signup and view all the answers

<p>Reduced corneal denervation</p> Signup and view all the answers

<p>Primary closed-angle glaucoma</p> Signup and view all the answers

<p>Phakic IOL</p> Signup and view all the answers

<p>To flatten the increased curvature of the cornea</p> Signup and view all the answers

<p>Axial hypermetropia</p> Signup and view all the answers

<p>Nutritional disturbance of the lens</p> Signup and view all the answers

<p>Blurring of vision for near work</p> Signup and view all the answers

<p>-0.5D to -9.00D</p> Signup and view all the answers

<p>Minus (concave) lenses</p> Signup and view all the answers

<p>It is usually congenital and can be induced by surgical scars.</p> Signup and view all the answers

<p>Simple astigmatism</p> Signup and view all the answers

<p>Cylindrical lenses</p> Signup and view all the answers

<p>Tilted intraocular lens (IOL)</p> Signup and view all the answers

<p>Blurring of vision</p> Signup and view all the answers

<p>The horizontal meridian is more curved than the vertical meridian.</p> Signup and view all the answers

<p>Treatment outcomes for LASIK</p> Signup and view all the answers

<p>Keratometer</p> Signup and view all the answers

<p>Increased corneal thickness</p> Signup and view all the answers

<p>Adding material to the periphery of the cornea</p> Signup and view all the answers

<p>Results tend to regress over time</p> Signup and view all the answers

<p>Flap thickness should range between 100 - 120 microns</p> Signup and view all the answers

<p>Cornea ectatic diseases like keratoconus</p> Signup and view all the answers

<p>They may cause corneal hypoxia and associated edema.</p> Signup and view all the answers

<p>Allows for rapid visual recovery</p> Signup and view all the answers

<p>Gas permeable lenses</p> Signup and view all the answers

<p>Encouraging the natural healing process in corneal issues</p> Signup and view all the answers

<p>Vision refractive correction</p> Signup and view all the answers

<p>Mild to moderate hyperopia</p> Signup and view all the answers

<p>Gas permeable lenses</p> Signup and view all the answers

<p>Their hydrophilic nature</p> Signup and view all the answers

<p>They are less stable than hard lenses.</p> Signup and view all the answers

<p>HEMA</p> Signup and view all the answers

<p>They provide better optics and a wider field of view.</p> Signup and view all the answers

<p>Induced astigmatism</p> Signup and view all the answers

<p>It provides better vision than no lens</p> Signup and view all the answers

<p>Previous ocular surgery</p> Signup and view all the answers

<p>In front of the iris</p> Signup and view all the answers

<p>Loss of natural accommodation</p> Signup and view all the answers

<p>Tends to decrease significantly</p> Signup and view all the answers

<p>Active anterior segment disease</p> Signup and view all the answers

<p>Retinal detachment</p> Signup and view all the answers

<p>Endothelial cell loss</p> Signup and view all the answers

<p>Iris atrophy</p> Signup and view all the answers

<p>Vaulted anteriorly to avoid contact with the lens capsule</p> Signup and view all the answers

<p>Cataract extraction</p> Signup and view all the answers

<p>Photodisruption</p> Signup and view all the answers

<p>Iatrogenic inverted implantation</p> Signup and view all the answers

<p>Pupillary block</p> Signup and view all the answers

<p>Inadequate flap thickness</p> Signup and view all the answers