Archives: Lessons

Dedicating additional time to challenging concepts through extra practice is essential for solidifying comprehension and mastery. We encourage you to assess your knowledge on determining the type of astigmatism (with-the-rule, against-the-rule, or oblique) with the following practice problems. The answer key is provided on the last page of the document. The English version of the … Continued

Dedicating additional time to challenging concepts through extra practice is essential for solidifying comprehension and mastery. We encourage you to assess your knowledge on determining the power of a spherical rigid lens with the following practice problems. The answer key is provided on the last page of the document. The English version of the Practice … Continued

Dedicating additional time to challenging concepts through extra practice is essential for solidifying comprehension and mastery. We encourage you to assess your knowledge on calculating effective and compensated power using the vertex distance rule of thumb and formula with the following practice problems. The answer key is provided on the last page of the document. … Continued

Summary Keratoconus is a complex, multifactorial condition with several known risk factors, including genetic influences. While there is no cure for the condition, there have been significant advances in treatment modalities to address the structural manifestations of the condition, rather than simply palliating its visual consequences. Specifically, CXL has been the biggest advance in this … Continued

Gene therapy The genetic component of keratoconus etiology, along with its biophysical properties, make it an ideal target for gene therapy. The goal of gene therapy is to use a viral vector to integrate into the target cell DNA and modify its gene sequence. Once the gene sequence has been regulated, normal proteins can be … Continued

Bowman layer transplantation The physiologic purpose of Bowman’s layer is unclear, but it is thought to play a role in the biomechanical stability of the cornea. In keratoconus, confocal microscopy consistently shows fragmentation of Bowman’s layer, and this is thought to play a role in corneal fragility. A surgical technique called Bowman Layer Transplantation was … Continued

Corneal transplantation Despite attempts at slowing the progression of keratoconus, sometimes corneal transplantation becomes necessary. Deep anterior lamellar keratoplasty (DALK) is generally the preferred surgery, provided that the Descemet’s-endothelial complex (DEC) is intact. If the DEC is compromised, however, full-thickness penetrating keratoplasty (PKP) becomes necessary. The collaborative longitudinal evaluation of keratoconus (CLEK) study found a corneal … Continued

Summary Keratoconus is a complex, multifactorial condition with several known risk factors, including genetic influences. While there is no cure for the condition, there have been significant advances in treatment modalities to address the structural manifestations of the condition, rather than simply palliating its visual consequences. Specifically, CXL has been the biggest advance in this … Continued

Gene therapy The genetic component of keratoconus etiology, along with its biophysical properties, make it an ideal target for gene therapy. The goal of gene therapy is to use a viral vector to integrate into the target cell DNA and modify its gene sequence. Once the gene sequence has been regulated, normal proteins can be … Continued

Bowman layer transplantation The physiologic purpose of Bowman’s layer is unclear, but it is thought to play a role in the biomechanical stability of the cornea. In keratoconus, confocal microscopy consistently shows fragmentation of Bowman’s layer, and this is thought to play a role in corneal fragility. A surgical technique called Bowman Layer Transplantation was … Continued

Corneal transplantation Despite attempts at slowing the progression of keratoconus, sometimes corneal transplantation becomes necessary. Deep anterior lamellar keratoplasty (DALK) is generally the preferred surgery, provided that the Descemet’s-endothelial complex (DEC) is intact. If the DEC is compromised, however, full-thickness penetrating keratoplasty (PKP) becomes necessary. The collaborative longitudinal evaluation of keratoconus (CLEK) study found a corneal … Continued

CXL-Treatment-Progress In 2016, the iLink platform (Photrexa Viscous 0.146% riboflavin 5ʹ-phosphate in 20% dextran ophthalmic solution, Photrexa 0.146% riboflavin 5ʹ-phosphate ophthalmic solution and the KXL System, Glaukos) was approved by the Food and Drug Administration (FDA) for the treatment of progressive keratoconus and corneal ectasia following refractive surgery (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8315767/). To date, it is the only … Continued